/*
    * DavMail POP/IMAP/SMTP/CalDav/LDAP Exchange Gateway
    * Copyright (C) 2009  Mickael Guessant
    *
    * This program is free software; you can redistribute it and/or
    * modify it under the terms of the GNU General Public License
    * as published by the Free Software Foundation; either version 2
    * of the License, or (at your option) any later version.
    *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   */
  package davmail.exchange;
  
  import davmail.BundleMessage;
  import davmail.Settings;
  import davmail.exception.DavMailException;
  import davmail.exception.HttpForbiddenException;
  import davmail.exception.HttpNotFoundException;
  import davmail.http.URIUtil;
  import davmail.ui.NotificationDialog;
  import davmail.util.StringUtil;
  import org.apache.log4j.Logger;
  
  import javax.mail.MessagingException;
  import javax.mail.internet.InternetAddress;
  import javax.mail.internet.InternetHeaders;
  import javax.mail.internet.MimeMessage;
  import javax.mail.internet.MimeMultipart;
  import javax.mail.internet.MimePart;
  import javax.mail.util.SharedByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStreamWriter;
  import java.io.StringReader;
  import java.net.NoRouteToHostException;
  import java.net.UnknownHostException;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.nio.file.Paths;
  import java.text.ParseException;
  import java.text.SimpleDateFormat;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Calendar;
  import java.util.Collections;
  import java.util.Date;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Properties;
  import java.util.ResourceBundle;
  import java.util.Set;
  import java.util.SimpleTimeZone;
  import java.util.TimeZone;
  import java.util.TreeMap;
  import java.util.UUID;
  
  /**
   * Exchange session through Outlook Web Access (DAV)
   */
  public abstract class ExchangeSession {
  
      protected static final Logger LOGGER = Logger.getLogger("davmail.exchange.ExchangeSession");
  
      /**
       * Reference GMT timezone to format dates
       */
      public static final SimpleTimeZone GMT_TIMEZONE = new SimpleTimeZone(0, "GMT");
  
      protected static final int FREE_BUSY_INTERVAL = 15;
  
      protected static final String PUBLIC_ROOT = "/public/";
      protected static final String CALENDAR = "calendar";
      protected static final String TASKS = "tasks";
      /**
       * Contacts folder logical name
       */
      public static final String CONTACTS = "contacts";
      protected static final String ADDRESSBOOK = "addressbook";
      protected static final String ARCHIVE = "Archive";
      protected static final String INBOX = "INBOX";
      protected static final String LOWER_CASE_INBOX = "inbox";
      protected static final String MIXED_CASE_INBOX = "Inbox";
      protected static final String SENT = "Sent";
      protected static final String SENDMSG = "##DavMailSubmissionURI##";
      protected static final String DRAFTS = "Drafts";
      protected static final String TRASH = "Trash";
     protected static final String JUNK = "Junk";
     protected static final String UNSENT = "Unsent Messages";
 
     protected static final List<String> SPECIAL = Arrays.asList(SENT, DRAFTS, TRASH, JUNK);
 
     // see https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxomsg/87a8b6b8-59a4-4859-9dcd-8b0f36e3d729
     protected static final String REPLYTOSENDER = "102";
     protected static final String REPLYTOALL = "103";
     protected static final String FORWARD = "104";
 
     protected static final String REPLIED_ICON = "261";
     protected static final String FORWARDED_ICON = "262";
 
     static {
         // Adjust Mime decoder settings
         System.setProperty("mail.mime.ignoreunknownencoding", "true");
         System.setProperty("mail.mime.decodetext.strict", "false");
     }
 
     protected String publicFolderUrl;
 
     /**
      * Base user mailboxes path (used to select folder)
      */
     protected String mailPath;
     protected String rootPath;
     protected String email;
     protected String alias;
     /**
      * Lower case Caldav path to the current user mailbox.
      * /users/<i>email</i>
      */
     protected String currentMailboxPath;
 
     protected String userName;
 
     protected String serverVersion;
 
     protected static final String YYYY_MM_DD_HH_MM_SS = "yyyy/MM/dd HH:mm:ss";
     private static final String YYYYMMDD_T_HHMMSS_Z = "yyyyMMdd'T'HHmmss'Z'";
     protected static final String YYYY_MM_DD_T_HHMMSS_Z = "yyyy-MM-dd'T'HH:mm:ss'Z'";
     private static final String YYYY_MM_DD = "yyyy-MM-dd";
     private static final String YYYY_MM_DD_T_HHMMSS_SSS_Z = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
 
     public ExchangeSession() {
         // empty constructor
     }
 
     /**
      * Close session.
      * Shutdown http client connection manager
      */
     public abstract void close();
 
     /**
      * Format date to exchange search format.
      *
      * @param date date object
      * @return formatted search date
      */
     public abstract String formatSearchDate(Date date);
 
     /**
      * Return standard zulu date formatter.
      *
      * @return zulu date formatter
      */
     public static SimpleDateFormat getZuluDateFormat() {
         SimpleDateFormat dateFormat = new SimpleDateFormat(YYYYMMDD_T_HHMMSS_Z, Locale.ENGLISH);
         dateFormat.setTimeZone(GMT_TIMEZONE);
         return dateFormat;
     }
 
     protected static SimpleDateFormat getVcardBdayFormat() {
         SimpleDateFormat dateFormat = new SimpleDateFormat(YYYY_MM_DD, Locale.ENGLISH);
         dateFormat.setTimeZone(GMT_TIMEZONE);
         return dateFormat;
     }
 
     protected static SimpleDateFormat getExchangeDateFormat(String value) {
         SimpleDateFormat dateFormat;
         if (value.length() == 8) {
             dateFormat = new SimpleDateFormat("yyyyMMdd", Locale.ENGLISH);
             dateFormat.setTimeZone(GMT_TIMEZONE);
         } else if (value.length() == 15) {
             dateFormat = new SimpleDateFormat("yyyyMMdd'T'HHmmss", Locale.ENGLISH);
             dateFormat.setTimeZone(GMT_TIMEZONE);
         } else if (value.length() == 16) {
             dateFormat = new SimpleDateFormat("yyyyMMdd'T'HHmmss'Z'", Locale.ENGLISH);
             dateFormat.setTimeZone(GMT_TIMEZONE);
         } else {
             dateFormat = ExchangeSession.getExchangeZuluDateFormat();
         }
         return dateFormat;
     }
 
     protected static SimpleDateFormat getExchangeZuluDateFormat() {
         SimpleDateFormat dateFormat = new SimpleDateFormat(YYYY_MM_DD_T_HHMMSS_Z, Locale.ENGLISH);
         dateFormat.setTimeZone(GMT_TIMEZONE);
         return dateFormat;
     }
 
     protected static SimpleDateFormat getExchangeZuluDateFormatMillisecond() {
         SimpleDateFormat dateFormat = new SimpleDateFormat(YYYY_MM_DD_T_HHMMSS_SSS_Z, Locale.ENGLISH);
         dateFormat.setTimeZone(GMT_TIMEZONE);
         return dateFormat;
     }
 
     protected static Date parseDate(String dateString) throws ParseException {
         SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
         dateFormat.setTimeZone(GMT_TIMEZONE);
         return dateFormat.parse(dateString);
     }
 
 
     /**
      * Test if the session expired.
      *
      * @return true if this session expired
      * @throws NoRouteToHostException on error
      * @throws UnknownHostException   on error
      */
     public boolean isExpired() throws NoRouteToHostException, UnknownHostException {
         boolean isExpired = false;
         try {
             getFolder("");
         } catch (UnknownHostException | NoRouteToHostException exc) {
             throw exc;
         } catch (IOException e) {
             isExpired = true;
         }
 
         return isExpired;
     }
 
     protected abstract void buildSessionInfo(java.net.URI uri) throws IOException;
 
     /**
      * Create a message in the specified folder.
      * Will overwrite an existing message with the same subject in the same folder
      *
      * @param folderPath  Exchange folder path
      * @param messageName message name
      * @param properties  message properties (flags)
      * @param mimeMessage MIME message
      * @throws IOException when unable to create message
      */
     public abstract Message createMessage(String folderPath, String messageName, HashMap<String, String> properties, MimeMessage mimeMessage) throws IOException;
 
     /**
      * Update given properties on message.
      *
      * @param message    Exchange message
      * @param properties Webdav properties map
      * @throws IOException on error
      */
     public abstract void updateMessage(Message message, Map<String, String> properties) throws IOException;
 
 
     /**
      * Delete Exchange message.
      *
      * @param message Exchange message
      * @throws IOException on error
      */
     public abstract void deleteMessage(Message message) throws IOException;
 
     /**
      * Get raw MIME message content
      *
      * @param message Exchange message
      * @return message body
      * @throws IOException on error
      */
     protected abstract byte[] getContent(Message message) throws IOException;
 
     protected static final Set<String> POP_MESSAGE_ATTRIBUTES = new HashSet<>();
 
     static {
         POP_MESSAGE_ATTRIBUTES.add("uid");
         POP_MESSAGE_ATTRIBUTES.add("imapUid");
         POP_MESSAGE_ATTRIBUTES.add("messageSize");
     }
 
     /**
      * Return folder message list with id and size only (for POP3 listener).
      *
      * @param folderName Exchange folder name
      * @return folder message list
      * @throws IOException on error
      */
     public MessageList getAllMessageUidAndSize(String folderName) throws IOException {
         return searchMessages(folderName, POP_MESSAGE_ATTRIBUTES, null);
     }
 
     protected static final Set<String> IMAP_MESSAGE_ATTRIBUTES = new HashSet<>();
 
     static {
         IMAP_MESSAGE_ATTRIBUTES.add("permanenturl");
         IMAP_MESSAGE_ATTRIBUTES.add("urlcompname");
         IMAP_MESSAGE_ATTRIBUTES.add("uid");
         IMAP_MESSAGE_ATTRIBUTES.add("messageSize");
         IMAP_MESSAGE_ATTRIBUTES.add("imapUid");
         IMAP_MESSAGE_ATTRIBUTES.add("junk");
         IMAP_MESSAGE_ATTRIBUTES.add("flagStatus");
         IMAP_MESSAGE_ATTRIBUTES.add("messageFlags");
         IMAP_MESSAGE_ATTRIBUTES.add("lastVerbExecuted");
         IMAP_MESSAGE_ATTRIBUTES.add("read");
         IMAP_MESSAGE_ATTRIBUTES.add("deleted");
         IMAP_MESSAGE_ATTRIBUTES.add("date");
         IMAP_MESSAGE_ATTRIBUTES.add("lastmodified");
         // OSX IMAP requests content-class
         IMAP_MESSAGE_ATTRIBUTES.add("contentclass");
         IMAP_MESSAGE_ATTRIBUTES.add("keywords");
     }
 
     protected static final Set<String> UID_MESSAGE_ATTRIBUTES = new HashSet<>();
 
     static {
         UID_MESSAGE_ATTRIBUTES.add("uid");
     }
 
     /**
      * Get all folder messages.
      *
      * @param folderPath Exchange folder name
      * @return message list
      * @throws IOException on error
      */
     public MessageList searchMessages(String folderPath) throws IOException {
         return searchMessages(folderPath, IMAP_MESSAGE_ATTRIBUTES, null);
     }
 
     /**
      * Search folder for messages matching conditions, with attributes needed by IMAP listener.
      *
      * @param folderName Exchange folder name
      * @param condition  search filter
      * @return message list
      * @throws IOException on error
      */
     public MessageList searchMessages(String folderName, Condition condition) throws IOException {
         return searchMessages(folderName, IMAP_MESSAGE_ATTRIBUTES, condition);
     }
 
     /**
      * Search folder for messages matching conditions, with given attributes.
      *
      * @param folderName Exchange folder name
      * @param attributes requested Webdav attributes
      * @param condition  search filter
      * @return message list
      * @throws IOException on error
      */
     public abstract MessageList searchMessages(String folderName, Set<String> attributes, Condition condition) throws IOException;
 
     /**
      * Get server version (Exchange2003, Exchange2007 or Exchange2010)
      *
      * @return server version
      */
     public String getServerVersion() {
         return serverVersion;
     }
 
     public enum Operator {
         Or, And, Not, IsEqualTo,
         IsGreaterThan, IsGreaterThanOrEqualTo,
         IsLessThan, IsLessThanOrEqualTo,
         IsNull, IsTrue, IsFalse,
         Like, StartsWith, Contains
     }
 
     /**
      * Exchange search filter.
      */
     public interface Condition {
         /**
          * Append condition to buffer.
          *
          * @param buffer search filter buffer
          */
         void appendTo(StringBuilder buffer);
 
         /**
          * True if condition is empty.
          *
          * @return true if condition is empty
          */
         boolean isEmpty();
 
         /**
          * Test if the contact matches current condition.
          *
          * @param contact Exchange Contact
          * @return true if contact matches condition
          */
         boolean isMatch(ExchangeSession.Contact contact);
     }
 
     /**
      * Attribute condition.
      */
     public abstract static class AttributeCondition implements Condition {
         protected final String attributeName;
         protected final Operator operator;
         protected final String value;
 
         protected AttributeCondition(String attributeName, Operator operator, String value) {
             this.attributeName = attributeName;
             this.operator = operator;
             this.value = value;
         }
 
         public boolean isEmpty() {
             return false;
         }
 
         /**
          * Get attribute name.
          *
          * @return attribute name
          */
         public String getAttributeName() {
             return attributeName;
         }
 
         /**
          * Condition value.
          *
          * @return value
          */
         public String getValue() {
             return value;
         }
 
     }
 
     /**
      * Multiple condition.
      */
     public abstract static class MultiCondition implements Condition {
         protected final Operator operator;
         protected final List<Condition> conditions;
 
         protected MultiCondition(Operator operator, Condition... conditions) {
             this.operator = operator;
             this.conditions = new ArrayList<>();
             for (Condition condition : conditions) {
                 if (condition != null) {
                     this.conditions.add(condition);
                 }
             }
         }
 
         /**
          * Conditions list.
          *
          * @return conditions
          */
         public List<Condition> getConditions() {
             return conditions;
         }
 
         /**
          * Condition operator.
          *
          * @return operator
          */
         public Operator getOperator() {
             return operator;
         }
 
         /**
          * Add a new condition.
          *
          * @param condition single condition
          */
         public void add(Condition condition) {
             if (condition != null) {
                 conditions.add(condition);
             }
         }
 
         @Override
         public boolean isEmpty() {
             return getActualConditionCount() == 0;
         }
 
         protected int getActualConditionCount() {
             int count = 0;
             for (Condition condition : conditions) {
                 if (!condition.isEmpty()) {
                     count++;
                 }
             }
             return count;
         }
 
         public boolean isMatch(ExchangeSession.Contact contact) {
             if (operator == Operator.And) {
                 for (Condition condition : conditions) {
                     if (!condition.isMatch(contact)) {
                         return false;
                     }
                 }
                 return true;
             } else if (operator == Operator.Or) {
                 for (Condition condition : conditions) {
                     if (condition.isMatch(contact)) {
                         return true;
                     }
                 }
                 return false;
             } else {
                 return false;
             }
         }
 
     }
 
     /**
      * Not condition.
      */
     public abstract static class NotCondition implements Condition {
         protected final Condition condition;
 
         protected NotCondition(Condition condition) {
             this.condition = condition;
         }
 
         public boolean isEmpty() {
             return condition.isEmpty();
         }
 
         public boolean isMatch(ExchangeSession.Contact contact) {
             return !condition.isMatch(contact);
         }
     }
 
     /**
      * Single search filter condition.
      */
     public abstract static class MonoCondition implements Condition {
         protected final String attributeName;
         protected final Operator operator;
 
         protected MonoCondition(String attributeName, Operator operator) {
             this.attributeName = attributeName;
             this.operator = operator;
         }
 
         public boolean isEmpty() {
             return false;
         }
 
         public boolean isMatch(ExchangeSession.Contact contact) {
             String actualValue = contact.get(attributeName);
             return (operator == Operator.IsNull && actualValue == null) ||
                     (operator == Operator.IsFalse && "false".equals(actualValue)) ||
                     (operator == Operator.IsTrue && "true".equals(actualValue));
         }
     }
 
     /**
      * And search filter.
      *
      * @param condition search conditions
      * @return condition
      */
     public abstract MultiCondition and(Condition... condition);
 
     /**
      * Or search filter.
      *
      * @param condition search conditions
      * @return condition
      */
     public abstract MultiCondition or(Condition... condition);
 
     /**
      * Not search filter.
      *
      * @param condition search condition
      * @return condition
      */
     public abstract Condition not(Condition condition);
 
     /**
      * Equals condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition isEqualTo(String attributeName, String value);
 
     /**
      * Equals condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition isEqualTo(String attributeName, int value);
 
     /**
      * MIME header equals condition.
      *
      * @param headerName MIME header name
      * @param value      attribute value
      * @return condition
      */
     public abstract Condition headerIsEqualTo(String headerName, String value);
 
     /**
      * Greater than or equals condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition gte(String attributeName, String value);
 
     /**
      * Greater than condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition gt(String attributeName, String value);
 
     /**
      * Lower than condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition lt(String attributeName, String value);
 
     /**
      * Lower than or equals condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     @SuppressWarnings({"UnusedDeclaration"})
     public abstract Condition lte(String attributeName, String value);
 
     /**
      * Contains condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition contains(String attributeName, String value);
 
     /**
      * Starts with condition.
      *
      * @param attributeName logical Exchange attribute name
      * @param value         attribute value
      * @return condition
      */
     public abstract Condition startsWith(String attributeName, String value);
 
     /**
      * Is null condition.
      *
      * @param attributeName logical Exchange attribute name
      * @return condition
      */
     public abstract Condition isNull(String attributeName);
 
     /**
      * Exists condition.
      *
      * @param attributeName logical Exchange attribute name
      * @return condition
      */
     public abstract Condition exists(String attributeName);
 
     /**
      * Is true condition.
      *
      * @param attributeName logical Exchange attribute name
      * @return condition
      */
     public abstract Condition isTrue(String attributeName);
 
     /**
      * Is false condition.
      *
      * @param attributeName logical Exchange attribute name
      * @return condition
      */
     public abstract Condition isFalse(String attributeName);
 
     /**
      * Search mail and generic folders under given folder.
      * Exclude calendar and contacts folders
      *
      * @param folderName Exchange folder name
      * @param recursive  deep search if true
      * @return list of folders
      * @throws IOException on error
      */
     public List<Folder> getSubFolders(String folderName, boolean recursive, boolean wildcard) throws IOException {
         MultiCondition folderCondition = and();
         if (!Settings.getBooleanProperty("davmail.imapIncludeSpecialFolders", false)) {
             folderCondition.add(or(isEqualTo("folderclass", "IPF.Note"),
                     isEqualTo("folderclass", "IPF.Note.Microsoft.Conversation"),
                     isNull("folderclass")));
         }
         if (wildcard) {
             folderCondition.add(startsWith("displayname", folderName));
             folderName = "";
         }
         List<Folder> results = getSubFolders(folderName, folderCondition,
                 recursive);
         // need to include base folder in recursive search, except on root on personal and shared mailboxes
         if (recursive && !getSubfolderPath(folderName).isEmpty()) {
             results.add(getFolder(folderName));
         }
 
         return results;
     }
 
     /**
      * Search calendar folders under given folder.
      *
      * @param folderName Exchange folder name
      * @param recursive  deep search if true
      * @return list of folders
      * @throws IOException on error
      */
     public List<Folder> getSubCalendarFolders(String folderName, boolean recursive) throws IOException {
         return getSubFolders(folderName, isEqualTo("folderclass", "IPF.Appointment"), recursive);
     }
 
 
     /**
      * Extract sub folder path from folder path.
      * Removed shared folder absolute path prefix.
      * @param folderPath input folder path
      * @return actual folder path inside mailbox
      */
     public String getSubfolderPath(String folderPath) {
         String baseFolderPath = folderPath;
         if (baseFolderPath.startsWith("/users/")) {
             int index = baseFolderPath.indexOf('/', "/users/".length());
             if (index >= 0) {
                 baseFolderPath = baseFolderPath.substring(index + 1);
             }
         }
         return baseFolderPath;
     }
     
     /**
      * Search folders under given folder matching filter.
      *
      * @param folderName Exchange folder name
      * @param condition  search filter
      * @param recursive  deep search if true
      * @return list of folders
      * @throws IOException on error
      */
     public abstract List<Folder> getSubFolders(String folderName, Condition condition, boolean recursive) throws IOException;
 
     /**
      * Delete oldest messages in trash.
      * keepDelay is the number of days to keep messages in trash before delete
      *
      * @throws IOException when unable to purge messages
      */
     public void purgeOldestTrashAndSentMessages() throws IOException {
         int keepDelay = Settings.getIntProperty("davmail.keepDelay");
         if (keepDelay != 0) {
             purgeOldestFolderMessages(TRASH, keepDelay);
         }
         // this is a new feature, default is : do nothing
         int sentKeepDelay = Settings.getIntProperty("davmail.sentKeepDelay");
         if (sentKeepDelay != 0) {
             purgeOldestFolderMessages(SENT, sentKeepDelay);
         }
     }
 
     protected void purgeOldestFolderMessages(String folderPath, int keepDelay) throws IOException {
         Calendar cal = Calendar.getInstance();
         cal.add(Calendar.DAY_OF_MONTH, -keepDelay);
         LOGGER.debug("Delete messages in " + folderPath + " not modified since " + cal.getTime());
 
         MessageList messages = searchMessages(folderPath, UID_MESSAGE_ATTRIBUTES,
                 lt("lastmodified", formatSearchDate(cal.getTime())));
 
         for (Message message : messages) {
             message.delete();
         }
     }
 
     /**
      * Moves Resent headers to standard headers
      */
     protected void convertResentHeader(MimeMessage mimeMessage, String headerName) throws MessagingException {
         String[] resentHeader = mimeMessage.getHeader("Resent-" + headerName);
         if (resentHeader != null) {
             mimeMessage.removeHeader("Resent-" + headerName);
             mimeMessage.removeHeader(headerName);
             for (String value : resentHeader) {
                 mimeMessage.addHeader(headerName, value);
             }
         }
     }
 
     protected String lastSentMessageId;
     protected List<String> lastRcptToRecipients;
 
     /**
      * Send the provided message to recipients.
      * Detect visible recipients in the message body to determine bcc recipients
      *
      * @param rcptToRecipients recipient list
      * @param mimeMessage      mime message
      * @throws IOException        on error
      * @throws MessagingException on error
      */
     public void sendMessage(List<String> rcptToRecipients, MimeMessage mimeMessage) throws IOException, MessagingException {
         // detect duplicate send command
         String messageId = mimeMessage.getMessageID();
         if (lastSentMessageId != null && lastSentMessageId.equals(messageId)) {
             // Resends duplicate message if allowed or recipients differ
             if (Settings.getBooleanProperty("davmail.smtpAllowDuplicateSend", false)) {
                 LOGGER.debug("Detected duplicate message id " + messageId + " but smtpAllowDuplicateSend is enabled, resending message");
             } else if (lastRcptToRecipients != null && !lastRcptToRecipients.equals(rcptToRecipients)) {
                 LOGGER.debug("Detected duplicate message id " + messageId + " but recipients differ, resending message");
             } else {
                 LOGGER.debug("Dropping message id " + messageId + ": already sent");
                 return;
             }
         }
         LOGGER.debug("Sending message id " + messageId);
 
         lastSentMessageId = messageId;
         lastRcptToRecipients = rcptToRecipients;
 
         convertResentHeader(mimeMessage, "From");
         convertResentHeader(mimeMessage, "To");
         convertResentHeader(mimeMessage, "Cc");
         convertResentHeader(mimeMessage, "Bcc");
         convertResentHeader(mimeMessage, "Message-Id");
 
         // do not allow send as another user on Exchange 2003
         if ("Exchange2003".equals(serverVersion) || Settings.getBooleanProperty("davmail.smtpStripFrom", false)) {
             mimeMessage.removeHeader("From");
         }
 
         // remove visible recipients from list
         Set<String> visibleRecipients = new HashSet<>();
         List<InternetAddress> recipients = getAllRecipients(mimeMessage);
         for (InternetAddress address : recipients) {
             visibleRecipients.add((address.getAddress().toLowerCase()));
         }
         for (String recipient : rcptToRecipients) {
             if (!visibleRecipients.contains(recipient.toLowerCase())) {
                 mimeMessage.addRecipient(javax.mail.Message.RecipientType.BCC, new InternetAddress(recipient));
             }
         }
         sendMessage(mimeMessage);
 
     }
 
     static final String[] RECIPIENT_HEADERS = {"to", "cc", "bcc"};
 
     protected List<InternetAddress> getAllRecipients(MimeMessage mimeMessage) throws MessagingException {
         List<InternetAddress> recipientList = new ArrayList<>();
         for (String recipientHeader : RECIPIENT_HEADERS) {
             final String recipientHeaderValue = mimeMessage.getHeader(recipientHeader, ",");
             if (recipientHeaderValue != null) {
                 // parse headers in non strict mode
                 recipientList.addAll(Arrays.asList(InternetAddress.parseHeader(recipientHeaderValue, false)));
             }
 
         }
         return recipientList;
     }
 
     /**
      * Send Mime message.
      *
      * @param mimeMessage MIME message
      * @throws IOException        on error
      * @throws MessagingException on error
      */
     public abstract void sendMessage(MimeMessage mimeMessage) throws IOException, MessagingException;
 
     /**
      * Get folder object.
      * Folder name can be logical names INBOX, Drafts, Trash or calendar,
      * or a path relative to user base folder or absolute path.
      *
      * @param folderPath folder path
      * @return Folder object
      * @throws IOException on error
      */
     public ExchangeSession.Folder getFolder(String folderPath) throws IOException {
         Folder folder = internalGetFolder(folderPath);
         if (isMainCalendar(folderPath)) {
             Folder taskFolder = internalGetFolder(TASKS);
             folder.ctag += taskFolder.ctag;
         }
         return folder;
     }
 
     protected abstract Folder internalGetFolder(String folderName) throws IOException;
 
     /**
      * Check folder ctag and reload messages as needed.
      *
      * @param currentFolder current folder
      * @return true if folder changed
      * @throws IOException on error
      */
     public boolean refreshFolder(Folder currentFolder) throws IOException {
         Folder newFolder = getFolder(currentFolder.folderPath);
         if (currentFolder.ctag == null || !currentFolder.ctag.equals(newFolder.ctag)
                 // ctag stamp is limited to second, check message count
                 || !(currentFolder.messageCount == newFolder.messageCount)
         ) {
             if (LOGGER.isDebugEnabled()) {
                 LOGGER.debug("Contenttag or count changed on " + currentFolder.folderPath +
                         " ctag: " + currentFolder.ctag + " => " + newFolder.ctag +
                         " count: " + currentFolder.messageCount + " => " + newFolder.messageCount
                         + ", reloading messages");
             }
             currentFolder.hasChildren = newFolder.hasChildren;
             currentFolder.noInferiors = newFolder.noInferiors;
             currentFolder.unreadCount = newFolder.unreadCount;
             currentFolder.ctag = newFolder.ctag;
             currentFolder.etag = newFolder.etag;
             if (newFolder.uidNext > currentFolder.uidNext) {
                 currentFolder.uidNext = newFolder.uidNext;
             }
             currentFolder.refreshMessages();
             return true;
         } else {
             return false;
         }
     }
 
     /**
      * Create Exchange message folder.
      *
      * @param folderName logical folder name
      * @throws IOException on error
      */
     public void createMessageFolder(String folderName) throws IOException {
         createFolder(folderName, "IPF.Note", null);
     }
 
     /**
      * Create Exchange calendar folder.
      *
      * @param folderName logical folder name
      * @param properties folder properties
      * @return status
      * @throws IOException on error
      */
     public int createCalendarFolder(String folderName, Map<String, String> properties) throws IOException {
         return createFolder(folderName, "IPF.Appointment", properties);
     }
 
     /**
      * Create Exchange contact folder.
      *
      * @param folderName logical folder name
      * @param properties folder properties
      * @throws IOException on error
      */
     public void createContactFolder(String folderName, Map<String, String> properties) throws IOException {
         createFolder(folderName, "IPF.Contact", properties);
     }
 
     /**
      * Create Exchange folder with given folder class.
      *
      * @param folderName  logical folder name
      * @param folderClass folder class
      * @param properties  folder properties
      * @return status
      * @throws IOException on error
      */
     public abstract int createFolder(String folderName, String folderClass, Map<String, String> properties) throws IOException;
 
     /**
      * Update Exchange folder properties.
      *
      * @param folderName logical folder name
      * @param properties folder properties
      * @return status
      * @throws IOException on error
      */
     public abstract int updateFolder(String folderName, Map<String, String> properties) throws IOException;
 
     /**
      * Delete Exchange folder.
      *
      * @param folderName logical folder name
      * @throws IOException on error
      */
     public abstract void deleteFolder(String folderName) throws IOException;
 
     /**
      * Copy message to target folder
      *
      * @param message      Exchange message
      * @param targetFolder target folder
      * @throws IOException on error
      */
     public abstract void copyMessage(Message message, String targetFolder) throws IOException;
 
     public void copyMessages(List<Message> messages, String targetFolder) throws IOException {
         for (Message message : messages) {
             copyMessage(message, targetFolder);
         }
     }
 
 
     /**
      * Move message to target folder
      *
      * @param message      Exchange message
      * @param targetFolder target folder
      * @throws IOException on error
      */
     public abstract void moveMessage(Message message, String targetFolder) throws IOException;
 
     public void moveMessages(List<Message> messages, String targetFolder) throws IOException {
         for (Message message : messages) {
             moveMessage(message, targetFolder);
         }
     }
 
     /**
      * Move folder to target name.
      *
      * @param folderName current folder name/path
      * @param targetName target folder name/path
      * @throws IOException on error
      */
     public abstract void moveFolder(String folderName, String targetName) throws IOException;
 
     /**
      * Move item from source path to target path.
      *
      * @param sourcePath item source path
      * @param targetPath item target path
      * @throws IOException on error
      */
     public abstract void moveItem(String sourcePath, String targetPath) throws IOException;
 
     protected abstract void moveToTrash(Message message) throws IOException;
 
     /**
      * Convert keyword value to IMAP flag.
      *
      * @param value keyword value
      * @return IMAP flag
      */
     public String convertKeywordToFlag(String value) {
         // first test for keyword in settings
         Properties flagSettings = Settings.getSubProperties("davmail.imapFlags");
         Enumeration<?> flagSettingsEnum = flagSettings.propertyNames();
         while (flagSettingsEnum.hasMoreElements()) {
             String key = (String) flagSettingsEnum.nextElement();
             if (value.equalsIgnoreCase(flagSettings.getProperty(key))) {
                 return key;
             }
         }
 
         ResourceBundle flagBundle = ResourceBundle.getBundle("imapflags");
         Enumeration<String> flagBundleEnum = flagBundle.getKeys();
         while (flagBundleEnum.hasMoreElements()) {
             String key = flagBundleEnum.nextElement();
             if (value.equalsIgnoreCase(flagBundle.getString(key))) {
                 return key;
             }
         }
 
         // fall back to raw value
         return value;
     }
 
     /**
      * Convert IMAP flag to keyword value.
      *
      * @param value IMAP flag
      * @return keyword value
      */
     public String convertFlagToKeyword(String value) {
         // first test for flag in settings
         Properties flagSettings = Settings.getSubProperties("davmail.imapFlags");
         // case insensitive lookup
         for (String key : flagSettings.stringPropertyNames()) {
             if (key.equalsIgnoreCase(value)) {
                 return flagSettings.getProperty(key);
             }
         }
 
         // fall back to predefined flags
         ResourceBundle flagBundle = ResourceBundle.getBundle("imapflags");
         for (String key : flagBundle.keySet()) {
             if (key.equalsIgnoreCase(value)) {
                 return flagBundle.getString(key);
             }
         }
 
         // fall back to raw value
         return value;
     }
 
     /**
      * Convert IMAP flags to keyword value.
      *
      * @param flags IMAP flags
      * @return keyword value
      */
     public String convertFlagsToKeywords(HashSet<String> flags) {
         HashSet<String> keywordSet = new HashSet<>();
         for (String flag : flags) {
             keywordSet.add(decodeKeyword(convertFlagToKeyword(flag)));
         }
         return StringUtil.join(keywordSet, ",");
     }
 
     protected String decodeKeyword(String keyword) {
         String result = keyword;
         if (keyword.contains("_x0028_") || keyword.contains("_x0029_")) {
             result = result.replace("_x0028_", "(")
                     .replace("_x0029_", ")");
         }
         return result;
     }
 
     protected String encodeKeyword(String keyword) {
         String result = keyword;
         if (keyword.indexOf('(') >= 0|| keyword.indexOf(')') >= 0) {
             result = result.replaceAll("\\(", "_x0028_")
                     .replaceAll("\\)", "_x0029_" );
         }
         return result;
     }
 
     /**
      * Exchange folder with IMAP properties
      */
     public class Folder {
         /**
          * Logical (IMAP) folder path.
          */
         public String folderPath;
 
         /**
          * Display Name.
          */
         public String displayName;
         /**
          * Folder class (PR_CONTAINER_CLASS).
          */
         public String folderClass;
         /**
          * Folder message count.
          */
         public int messageCount;
         /**
          * Folder unread message count.
          */
         public int unreadCount;
         /**
          * true if folder has subfolders (DAV:hassubs).
          */
         public boolean hasChildren;
         /**
          * true if folder has no subfolders (DAV:nosubs).
          */
         public boolean noInferiors;
         /**
          * Folder content tag (to detect folder content changes).
          */
         public String ctag;
         /**
          * Folder etag (to detect folder object changes).
          */
         public String etag;
         /**
          * Next IMAP uid
          */
         public long uidNext;
         /**
          * recent count
          */
         public int recent;
 
         /**
          * Folder message list, empty before loadMessages call.
          */
         public ExchangeSession.MessageList messages;
         /**
          * Permanent uid (PR_SEARCH_KEY) to IMAP UID map.
          */
         private final HashMap<String, Long> permanentUrlToImapUidMap = new HashMap<>();
 
         /**
          * Get IMAP folder flags.
          *
          * @return folder flags in IMAP format
          */
         public String getFlags() {
             String specialFlag = "";
             if (isSpecial()) {
                 specialFlag = "\\" + folderPath + " ";
             }
             if (noInferiors) {
                 return specialFlag + "\\NoInferiors";
             } else if (hasChildren) {
                 return specialFlag + "\\HasChildren";
             } else {
                 return specialFlag + "\\HasNoChildren";
             }
         }
 
         /**
          * Special folder flag (Sent, Drafts, Trash, Junk).
          * @return true if folder is special
          */
         public boolean isSpecial() {
             return SPECIAL.contains(folderPath);
         }
 
         /**
          * Load folder messages.
          *
          * @throws IOException on error
          */
         public void loadMessages() throws IOException {
             messages = ExchangeSession.this.searchMessages(folderPath, null);
             fixUids(messages);
             computeAttributes();
         }
 
         protected void computeAttributes() {
             recent = 0;
             for (Message message : messages) {
                 if (message.recent) {
                     recent++;
                 }
             }
             long computedUidNext = 1;
             if (!messages.isEmpty()) {
                 computedUidNext = messages.get(messages.size() - 1).getImapUid() + 1;
             }
             if (computedUidNext > uidNext) {
                 uidNext = computedUidNext;
             }
             // make sure message count matches current list count
             messageCount = messages.size();
 
             buildImapFlagMap();
         }
 
         public void refreshMessages() throws IOException {
             loadMessages();
         }
 
         /**
          * Search messages in folder matching query.
          *
          * @param condition search query
          * @return message list
          * @throws IOException on error
          */
         public MessageList searchMessages(Condition condition) throws IOException {
             MessageList localMessages = ExchangeSession.this.searchMessages(folderPath, condition);
             fixUids(localMessages);
             return localMessages;
         }
 
         /**
          * Restore previous uids changed by a PROPPATCH (flag change).
          *
          * @param messages message list
          */
         protected void fixUids(MessageList messages) {
             boolean sortNeeded = false;
             for (Message message : messages) {
                 if (permanentUrlToImapUidMap.containsKey(message.getPermanentId())) {
                     long previousUid = permanentUrlToImapUidMap.get(message.getPermanentId());
                     if (message.getImapUid() != previousUid) {
                         LOGGER.debug("Restoring IMAP uid " + message.getImapUid() + " -> " + previousUid + " for message " + message.getPermanentId());
                         message.setImapUid(previousUid);
                         sortNeeded = true;
                     }
                 } else {
                     // add message to uid map
                     permanentUrlToImapUidMap.put(message.getPermanentId(), message.getImapUid());
                 }
             }
             if (sortNeeded) {
                 Collections.sort(messages);
             }
         }
 
         /**
          * Folder message count.
          *
          * @return message count
          */
         public int count() {
             if (messages == null) {
                 return messageCount;
             } else {
                 return messages.size();
             }
         }
 
         /**
          * Compute IMAP uidnext.
          *
          * @return max(messageuids)+1
          */
         public long getUidNext() {
             return uidNext;
         }
 
         /**
          * Get message at index.
          *
          * @param index message index
          * @return message
          */
         public Message get(int index) {
             return messages.get(index);
         }
 
         private TreeMap<Long, String> imapFlagMap = new TreeMap<>();
 
         /**
          * Get current folder messages imap uids and flags
          *
          * @return imap uid list
          */
         public TreeMap<Long, String> getImapFlagMap() {
             return imapFlagMap;
         }
 
         public void buildImapFlagMap() {
             int previousMessageCount = imapFlagMap.size();
             // recreate an empty map to avoid erasing previous values in ImapConnection
             imapFlagMap = new TreeMap<>();
             for (ExchangeSession.Message message : messages) {
                 imapFlagMap.put(message.getImapUid(), message.getImapFlags());
             }
             LOGGER.debug("imapFlagMap size: " + previousMessageCount + " -> " + imapFlagMap.size());
         }
 
         /**
          * Calendar folder flag.
          *
          * @return true if this is a calendar folder
          */
         public boolean isCalendar() {
             return "IPF.Appointment".equals(folderClass);
         }
 
         /**
          * Contact folder flag.
          *
          * @return true if this is a calendar folder
          */
         public boolean isContact() {
             return "IPF.Contact".equals(folderClass);
         }
 
         /**
          * Task folder flag.
          *
          * @return true if this is a task folder
          */
         public boolean isTask() {
             return "IPF.Task".equals(folderClass);
         }
 
         /**
          * drop cached message
          */
         public void clearCache() {
             messages.cachedMimeContent = null;
             messages.cachedMimeMessage = null;
             messages.cachedMessageImapUid = 0;
         }
     }
 
     /**
      * Exchange message.
      */
     public abstract class Message implements Comparable<Message> {
         /**
          * enclosing message list
          */
         public MessageList messageList;
         /**
          * Message url.
          */
         public String messageUrl;
         /**
          * Message permanent url (does not change on message move).
          */
         public String permanentUrl;
         /**
          * Message uid.
          */
         public String uid;
         /**
          * Message content class.
          */
         public String contentClass;
         /**
          * Message keywords (categories).
          */
         public String keywords;
         /**
          * Message IMAP uid, unique in folder (x0e230003).
          */
         public long imapUid;
         /**
          * MAPI message size.
          */
         public int size;
         /**
          * Message date (urn:schemas:mailheader:date).
          */
         public String date;
 
         /**
          * Message flag: read.
          */
         public boolean read;
         /**
          * Message flag: deleted.
          */
         public boolean deleted;
         /**
          * Message flag: junk.
          */
         public boolean junk;
         /**
          * Message flag: flagged.
          */
         public boolean flagged;
         /**
          * Message flag: recent.
          */
         public boolean recent;
         /**
          * Message flag: draft.
          */
         public boolean draft;
         /**
          * Message flag: answered.
          */
         public boolean answered;
         /**
          * Message flag: forwarded.
          */
         public boolean forwarded;
 
         /**
          * Unparsed message content.
          */
         protected byte[] mimeContent;
 
         /**
          * Message content parsed in a MIME message.
          */
         protected MimeMessage mimeMessage;
 
         /**
          * Get permanent message id.
          * permanentUrl over WebDav or ItemId over EWS
          *
          * @return permanent id
          */
         public abstract String getPermanentId();
 
         /**
          * IMAP uid , unique in folder (x0e230003)
          *
          * @return IMAP uid
          */
         public long getImapUid() {
             return imapUid;
         }
 
         /**
          * Set IMAP uid.
          *
          * @param imapUid new uid
          */
         public void setImapUid(long imapUid) {
             this.imapUid = imapUid;
         }
 
         /**
          * Exchange uid.
          *
          * @return uid
          */
         public String getUid() {
             return uid;
         }
 
         /**
          * Return message flags in IMAP format.
          *
          * @return IMAP flags
          */
         public String getImapFlags() {
             StringBuilder buffer = new StringBuilder();
             if (read) {
                 buffer.append("\\Seen ");
             }
             if (deleted) {
                 buffer.append("\\Deleted ");
             }
             if (recent) {
                 buffer.append("\\Recent ");
             }
             if (flagged) {
                 buffer.append("\\Flagged ");
             }
             if (junk) {
                 buffer.append("Junk ");
             }
             if (draft) {
                 buffer.append("\\Draft ");
             }
             if (answered) {
                 buffer.append("\\Answered ");
             }
             if (forwarded) {
                 buffer.append("$Forwarded ");
             }
             if (keywords != null) {
                 for (String keyword : keywords.split(",")) {
                     buffer.append(encodeKeyword(convertKeywordToFlag(keyword))).append(" ");
                 }
             }
             return buffer.toString().trim();
         }
 
         /**
          * Load message content in a Mime message
          *
          * @throws IOException        on error
          * @throws MessagingException on error
          */
         public void loadMimeMessage() throws IOException, MessagingException {
             if (mimeMessage == null) {
                 // try to get message content from cache
                 if (this.imapUid == messageList.cachedMessageImapUid
                         // make sure we never return null even with broken 0 uid message
                         && messageList.cachedMimeContent != null
                         && messageList.cachedMimeMessage != null) {
                     mimeContent = messageList.cachedMimeContent;
                     mimeMessage = messageList.cachedMimeMessage;
                     LOGGER.debug("Got message content for " + imapUid + " from cache");
                 } else {
                     // load and parse message
                     mimeContent = getContent(this);
                     mimeMessage = new MimeMessage(null, new SharedByteArrayInputStream(mimeContent));
                     // workaround for Exchange 2003 ActiveSync bug
                     if (mimeMessage.getHeader("MAIL FROM") != null) {
                         // find start of actual message
                         byte[] mimeContentCopy = new byte[((SharedByteArrayInputStream) mimeMessage.getRawInputStream()).available()];
                         int offset = mimeContent.length - mimeContentCopy.length;
                         // remove unwanted header
                         System.arraycopy(mimeContent, offset, mimeContentCopy, 0, mimeContentCopy.length);
                         mimeContent = mimeContentCopy;
                         mimeMessage = new MimeMessage(null, new SharedByteArrayInputStream(mimeContent));
                     }
                     LOGGER.debug("Downloaded full message content for IMAP UID " + imapUid + " (" + mimeContent.length + " bytes)");
                 }
             }
         }
 
         /**
          * Get message content as a Mime message.
          *
          * @return mime message
          * @throws IOException        on error
          * @throws MessagingException on error
          */
         public MimeMessage getMimeMessage() throws IOException, MessagingException {
             loadMimeMessage();
             return mimeMessage;
         }
 
         public Enumeration<?> getMatchingHeaderLinesFromHeaders(String[] headerNames) throws MessagingException {
             Enumeration<?> result = null;
             if (mimeMessage == null) {
                 // message not loaded, try to get headers only
                 InputStream headers = getMimeHeaders();
                 if (headers != null) {
                     InternetHeaders internetHeaders = new InternetHeaders(headers);
                     if (internetHeaders.getHeader("Subject") == null) {
                         // invalid header content
                         return null;
                     }
                     if (headerNames == null) {
                         result = internetHeaders.getAllHeaderLines();
                     } else {
                         result = internetHeaders.getMatchingHeaderLines(headerNames);
                     }
                 }
             }
             return result;
         }
 
         public Enumeration<?> getMatchingHeaderLines(String[] headerNames) throws MessagingException, IOException {
             Enumeration<?> result = getMatchingHeaderLinesFromHeaders(headerNames);
             if (result == null) {
                 if (headerNames == null) {
                     result = getMimeMessage().getAllHeaderLines();
                 } else {
                     result = getMimeMessage().getMatchingHeaderLines(headerNames);
                 }
 
             }
             return result;
         }
 
         protected abstract InputStream getMimeHeaders();
 
         /**
          * Get message body size.
          *
          * @return mime message size
          * @throws IOException        on error
          * @throws MessagingException on error
          */
         public int getMimeMessageSize() throws IOException, MessagingException {
             loadMimeMessage();
             return mimeContent.length;
         }
 
         /**
          * Get message body input stream.
          *
          * @return mime message InputStream
          * @throws IOException        on error
          * @throws MessagingException on error
          */
         public InputStream getRawInputStream() throws IOException, MessagingException {
             loadMimeMessage();
             return new SharedByteArrayInputStream(mimeContent);
         }
 
 
         /**
          * Drop mime message to avoid keeping message content in memory,
          * keep a single message in MessageList cache to handle chunked fetch.
          */
         public void dropMimeMessage() {
             // update single message cache
             if (mimeMessage != null) {
                 messageList.cachedMessageImapUid = imapUid;
                 messageList.cachedMimeContent = mimeContent;
                 messageList.cachedMimeMessage = mimeMessage;
             }
             // drop current message body to save memory
             mimeMessage = null;
             mimeContent = null;
         }
 
         public boolean isLoaded() {
             // check and retrieve cached content
             if (imapUid == messageList.cachedMessageImapUid) {
                 mimeContent = messageList.cachedMimeContent;
                 mimeMessage = messageList.cachedMimeMessage;
             }
             return mimeMessage != null;
         }
 
         /**
          * Delete message.
          *
          * @throws IOException on error
          */
         public void delete() throws IOException {
             deleteMessage(this);
         }
 
         /**
          * Move message to trash, mark message read.
          *
          * @throws IOException on error
          */
         public void moveToTrash() throws IOException {
             markRead();
 
             ExchangeSession.this.moveToTrash(this);
         }
 
         /**
          * Mark message as read.
          *
          * @throws IOException on error
          */
         public void markRead() throws IOException {
             HashMap<String, String> properties = new HashMap<>();
             properties.put("read", "1");
             updateMessage(this, properties);
         }
 
         /**
          * Comparator to sort messages by IMAP uid
          *
          * @param message other message
          * @return imapUid comparison result
          */
         public int compareTo(Message message) {
             long compareValue = (imapUid - message.imapUid);
             if (compareValue > 0) {
                 return 1;
             } else if (compareValue < 0) {
                 return -1;
             } else {
                 return 0;
             }
         }
 
         /**
          * Override equals, compare IMAP uids
          *
          * @param message other message
          * @return true if IMAP uids are equal
          */
         @Override
         public boolean equals(Object message) {
             return message instanceof Message && imapUid == ((Message) message).imapUid;
         }
 
         /**
          * Override hashCode, return imapUid hashcode.
          *
          * @return imapUid hashcode
          */
         @Override
         public int hashCode() {
             return Long.hashCode(imapUid);
         }
 
         public String removeFlag(String flag) {
             if (keywords != null) {
                 final String exchangeFlag = convertFlagToKeyword(flag);
                 Set<String> keywordSet = new HashSet<>();
                 String[] keywordArray = keywords.split(",");
                 for (String value : keywordArray) {
                     if (!value.equalsIgnoreCase(exchangeFlag)) {
                         keywordSet.add(value);
                     }
                 }
                 keywords = StringUtil.join(keywordSet, ",");
             }
             return keywords;
         }
 
         public String addFlag(String flag) {
             final String exchangeFlag = convertFlagToKeyword(flag);
             HashSet<String> keywordSet = new HashSet<>();
             boolean hasFlag = false;
             if (keywords != null) {
                 String[] keywordArray = keywords.split(",");
                 for (String value : keywordArray) {
                     keywordSet.add(value);
                     if (value.equalsIgnoreCase(exchangeFlag)) {
                         hasFlag = true;
                     }
                 }
             }
             if (!hasFlag) {
                 keywordSet.add(exchangeFlag);
             }
             keywords = StringUtil.join(keywordSet, ",");
             return keywords;
         }
 
         public String setFlags(HashSet<String> flags) {
             keywords = convertFlagsToKeywords(flags);
             return keywords;
         }
 
     }
 
     /**
      * Message list, includes a single message cache
      */
     public static class MessageList extends ArrayList<Message> {
         /**
          * Cached message content parsed in a MIME message.
          */
         protected transient MimeMessage cachedMimeMessage;
         /**
          * Cached message uid.
          */
         protected transient long cachedMessageImapUid;
         /**
          * Cached unparsed message
          */
         protected transient byte[] cachedMimeContent;
 
     }
 
     /**
      * Generic folder item.
      */
     public abstract static class Item extends HashMap<String, String> {
         public String folderPath;
         protected String itemName;
         protected String permanentUrl;
         /**
          * Display name.
          */
         public String displayName;
         /**
          * item etag
          */
         public String etag;
         protected String noneMatch;
 
         /**
          * Build item instance.
          *
          * @param folderPath folder path
          * @param itemName   item name class
          * @param etag       item etag
          * @param noneMatch  none match flag
          */
         public Item(String folderPath, String itemName, String etag, String noneMatch) {
             this.folderPath = folderPath;
             this.itemName = itemName;
             this.etag = etag;
             this.noneMatch = noneMatch;
         }
 
         /**
          * Default constructor.
          */
         protected Item() {
         }
 
         /**
          * Return item content type
          *
          * @return content type
          */
         public abstract String getContentType();
 
         /**
          * Retrieve item body from Exchange
          *
          * @return item body
          * @throws IOException on error
          */
         public abstract String getBody() throws IOException;
 
         /**
          * Get event name (file name part in URL).
          *
          * @return event name
          */
         public String getName() {
             return itemName;
         }
 
         /**
          * Get event etag (last change tag).
          *
          * @return event etag
          */
         public String getEtag() {
             return etag;
         }
 
         /**
          * Set item href.
          *
          * @param href item href
          */
         public void setHref(String href) {
             int index = href.lastIndexOf('/');
             if (index >= 0) {
                 folderPath = href.substring(0, index);
                 itemName = href.substring(index + 1);
             } else {
                 throw new IllegalArgumentException(href);
             }
         }
 
         /**
          * Return item href.
          *
          * @return item href
          */
         public String getHref() {
             return folderPath + '/' + itemName;
         }
 
         public void setItemName(String itemName) {
             this.itemName = itemName;
         }
     }
 
     /**
      * Contact object
      */
     public abstract class Contact extends Item {
 
         protected ArrayList<String> distributionListMembers = null;
         protected String vCardVersion;
 
         public Contact(String folderPath, String itemName, Map<String, String> properties, String etag, String noneMatch) {
             super(folderPath, itemName.endsWith(".vcf") ? itemName.substring(0, itemName.length() - 3) + "EML" : itemName, etag, noneMatch);
             this.putAll(properties);
         }
 
         protected Contact() {
         }
 
         public void setVCardVersion(String vCardVersion) {
             this.vCardVersion = vCardVersion;
         }
 
         public abstract ItemResult createOrUpdate() throws IOException;
 
         /**
          * Convert EML extension to vcf.
          *
          * @return item name
          */
         @Override
         public String getName() {
             String name = super.getName();
             if (name.endsWith(".EML")) {
                 name = name.substring(0, name.length() - 3) + "vcf";
             }
             return name;
         }
 
         /**
          * Set contact name
          *
          * @param name contact name
          */
         public void setName(String name) {
             this.itemName = name;
         }
 
         /**
          * Compute vcard uid from name.
          *
          * @return uid
          */
         public String getUid() {
             String uid = getName();
             int dotIndex = uid.lastIndexOf('.');
             if (dotIndex > 0) {
                 uid = uid.substring(0, dotIndex);
             }
             return URIUtil.encodePath(uid);
         }
 
         @Override
         public String getContentType() {
             return "text/vcard";
         }
 
         public void addMember(String member) {
             if (distributionListMembers == null) {
                 distributionListMembers = new ArrayList<>();
             }
             distributionListMembers.add(member);
         }
 
 
         @Override
         public String getBody() {
             // build RFC 2426 VCard from contact information
             VCardWriter writer = new VCardWriter();
             writer.startCard(vCardVersion);
             writer.appendProperty("UID", getUid());
             // common name
             String cn = get("cn");
             if (cn == null) {
                 cn = get("displayname");
             }
             String sn = get("sn");
             if (sn == null) {
                 sn = cn;
             }
             writer.appendProperty("FN", cn);
             // RFC 2426: Family Name, Given Name, Additional Names, Honorific Prefixes, and Honorific Suffixes
             writer.appendProperty("N", sn, get("givenName"), get("middlename"), get("personaltitle"), get("namesuffix"));
 
             if (distributionListMembers != null) {
                 writer.appendProperty("KIND", "group");
                 for (String member : distributionListMembers) {
                     writer.appendProperty("MEMBER", member);
                 }
             }
 
             writer.appendProperty("TEL;TYPE=cell", get("mobile"));
             writer.appendProperty("TEL;TYPE=work", get("telephoneNumber"));
             writer.appendProperty("TEL;TYPE=home", get("homePhone"));
             writer.appendProperty("TEL;TYPE=fax", get("facsimiletelephonenumber"));
             writer.appendProperty("TEL;TYPE=pager", get("pager"));
             writer.appendProperty("TEL;TYPE=car", get("othermobile"));
             writer.appendProperty("TEL;TYPE=home,fax", get("homefax"));
             writer.appendProperty("TEL;TYPE=isdn", get("internationalisdnnumber"));
             writer.appendProperty("TEL;TYPE=msg", get("otherTelephone"));
 
             writer.appendProperty("TEL;TYPE=work", get("otherBusinessTelephoneNumber"));
             writer.appendProperty("TEL;TYPE=home", get("otherHomePhone"));
 
             // The structured type value corresponds, in sequence, to the post office box; the extended address;
             // the street address; the locality (e.g., city); the region (e.g., state or province);
             // the postal code; the country name
             writer.appendProperty("ADR;TYPE=home",
                     get("homepostofficebox"), null, get("homeStreet"), get("homeCity"), get("homeState"), get("homePostalCode"), get("homeCountry"));
             writer.appendProperty("ADR;TYPE=work",
                     get("postofficebox"), get("roomnumber"), get("street"), get("l"), get("st"), get("postalcode"), get("co"));
             writer.appendProperty("ADR;TYPE=other",
                     get("otherpostofficebox"), null, get("otherstreet"), get("othercity"), get("otherstate"), get("otherpostalcode"), get("othercountry"));
 
             writer.appendProperty("EMAIL;TYPE=work", get("smtpemail1"));
             writer.appendProperty("EMAIL;TYPE=home", get("smtpemail2"));
             writer.appendProperty("EMAIL;TYPE=other", get("smtpemail3"));
 
             writer.appendProperty("ORG", get("o"), get("department"));
             writer.appendProperty("URL;TYPE=work", get("businesshomepage"));
             writer.appendProperty("URL;TYPE=home", get("personalHomePage"));
             writer.appendProperty("TITLE", get("title"));
             writer.appendProperty("NOTE", get("personalNotes"));
 
             writer.appendProperty("CUSTOM1", get("extensionattribute1"));
             writer.appendProperty("CUSTOM2", get("extensionattribute2"));
             writer.appendProperty("CUSTOM3", get("extensionattribute3"));
             writer.appendProperty("CUSTOM4", get("extensionattribute4"));
 
             writer.appendProperty("ROLE", get("profession"));
             writer.appendProperty("NICKNAME", get("nickname"));
             writer.appendProperty("X-AIM", get("im"));
 
             writer.appendProperty("BDAY", convertZuluDateToBday(get("bday")));
             writer.appendProperty("ANNIVERSARY", convertZuluDateToBday(get("anniversary")));
 
             String gender = get("gender");
             if ("1".equals(gender)) {
                 writer.appendProperty("SEX", "2");
             } else if ("2".equals(gender)) {
                 writer.appendProperty("SEX", "1");
             }
 
             writer.appendProperty("CATEGORIES", get("keywords"));
 
             writer.appendProperty("FBURL", get("fburl"));
 
             if ("1".equals(get("private"))) {
                 writer.appendProperty("CLASS", "PRIVATE");
             }
 
             writer.appendProperty("X-ASSISTANT", get("secretarycn"));
             writer.appendProperty("X-MANAGER", get("manager"));
             writer.appendProperty("X-SPOUSE", get("spousecn"));
 
             writer.appendProperty("REV", get("lastmodified"));
 
             ContactPhoto contactPhoto = null;
 
             if (Settings.getBooleanProperty("davmail.carddavReadPhoto", true)) {
                 if (("true".equals(get("haspicture")))) {
                     try {
                         contactPhoto = getContactPhoto(this);
                     } catch (IOException e) {
                         LOGGER.warn("Unable to get photo from contact " + this.get("cn"));
                     }
                 }
 
                 if (contactPhoto == null) {
                     contactPhoto = getADPhoto(get("smtpemail1"));
                 }
             }
 
             if (contactPhoto != null) {
                 writer.writeLine("PHOTO:data:"+contactPhoto.contentType+";base64," +contactPhoto.content);
             }
 
             writer.appendProperty("KEY1;X509;ENCODING=BASE64", get("msexchangecertificate"));
             writer.appendProperty("KEY2;X509;ENCODING=BASE64", get("usersmimecertificate"));
 
             writer.endCard();
             return writer.toString();
         }
     }
 
     /**
      * Calendar event object.
      */
     public abstract class Event extends Item {
         protected String contentClass;
         protected String subject;
         protected VCalendar vCalendar;
 
         public Event(String folderPath, String itemName, String contentClass, String itemBody, String etag, String noneMatch) throws IOException {
             super(folderPath, itemName, etag, noneMatch);
             this.contentClass = contentClass;
             fixICS(itemBody.getBytes(StandardCharsets.UTF_8), getCalendarEmail(folderPath), false);
             // fix task item name
             if (vCalendar.isTodo() && this.itemName.endsWith(".ics")) {
                 this.itemName = itemName.substring(0, itemName.length() - 3) + "EML";
             }
         }
 
         protected Event() {
         }
 
         @Override
         public String getContentType() {
             return "text/calendar;charset=UTF-8";
         }
 
         @Override
         public String getBody() throws IOException {
             if (vCalendar == null) {
                 fixICS(getEventContent(), getCalendarEmail(folderPath), true);
             }
             return vCalendar.toString();
         }
 
         protected HttpNotFoundException buildHttpNotFoundException(Exception e) {
             String message = "Unable to get event " + getName() + " subject: " + subject + " at " + permanentUrl + ": " + e.getMessage();
             LOGGER.warn(message);
             return new HttpNotFoundException(message);
         }
 
         /**
          * Retrieve item body from Exchange
          *
          * @return item content
          * @throws IOException on error
          */
         public abstract byte[] getEventContent() throws IOException;
 
         protected static final String TEXT_CALENDAR = "text/calendar";
         protected static final String APPLICATION_ICS = "application/ics";
 
         protected boolean isCalendarContentType(String contentType) {
             return TEXT_CALENDAR.regionMatches(true, 0, contentType, 0, TEXT_CALENDAR.length()) ||
                     APPLICATION_ICS.regionMatches(true, 0, contentType, 0, APPLICATION_ICS.length());
         }
 
         protected MimePart getCalendarMimePart(MimeMultipart multiPart) throws IOException, MessagingException {
             MimePart bodyPart = null;
             for (int i = 0; i < multiPart.getCount(); i++) {
                 String contentType = multiPart.getBodyPart(i).getContentType();
                 if (isCalendarContentType(contentType)) {
                     bodyPart = (MimePart) multiPart.getBodyPart(i);
                     break;
                 } else if (contentType.startsWith("multipart")) {
                     Object content = multiPart.getBodyPart(i).getContent();
                     if (content instanceof MimeMultipart) {
                         bodyPart = getCalendarMimePart((MimeMultipart) content);
                     }
                 }
             }
 
             return bodyPart;
         }
 
         /**
          * Load ICS content from MIME message input stream
          *
          * @param mimeInputStream mime message input stream
          * @return mime message ics attachment body
          * @throws IOException        on error
          * @throws MessagingException on error
          */
         protected byte[] getICS(InputStream mimeInputStream) throws IOException, MessagingException {
             byte[] result;
             MimeMessage mimeMessage = new MimeMessage(null, mimeInputStream);
             String[] contentClassHeader = mimeMessage.getHeader("Content-class");
             // task item, return null
             if (contentClassHeader != null && contentClassHeader.length > 0 && "urn:content-classes:task".equals(contentClassHeader[0])) {
                 return null;
             }
             Object mimeBody = mimeMessage.getContent();
             MimePart bodyPart = null;
             if (mimeBody instanceof MimeMultipart) {
                 bodyPart = getCalendarMimePart((MimeMultipart) mimeBody);
             } else if (isCalendarContentType(mimeMessage.getContentType())) {
                 // no multipart, single body
                 bodyPart = mimeMessage;
             }
 
 
             if (bodyPart != null) {
                 try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
                     bodyPart.getDataHandler().writeTo(baos);
                     result = baos.toByteArray();
                 }
             } else {
                 try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
                     mimeMessage.writeTo(baos);
                     throw new DavMailException("EXCEPTION_INVALID_MESSAGE_CONTENT", new String(baos.toByteArray(), StandardCharsets.UTF_8));
                 }
             }
             return result;
         }
 
         protected void fixICS(byte[] icsContent, String calendarEmail, boolean fromServer) throws IOException {
             if (LOGGER.isDebugEnabled() && fromServer) {
                 dumpIndex++;
                 String icsBody = new String(icsContent, StandardCharsets.UTF_8);
                 ICSCalendarValidator.ValidationResult vr = ICSCalendarValidator.validateWithDetails(icsBody);
                 dumpICS(icsBody, true, false);
                 LOGGER.debug("Vcalendar body ValidationResult: "+ vr.isValid() +" "+ vr.showReason());
                 LOGGER.debug("Vcalendar body received from server:\n" + icsBody);
             }
             vCalendar = new VCalendar(icsContent, calendarEmail, getVTimezone());
             vCalendar.fixVCalendar(fromServer);
             if (LOGGER.isDebugEnabled() && !fromServer) {
                 String resultString = vCalendar.toString();
                 ICSCalendarValidator.ValidationResult vr = ICSCalendarValidator.validateWithDetails(resultString);
                 LOGGER.debug("Fixed Vcalendar body ValidationResult: "+ vr.isValid() +" "+ vr.showReason());
                 LOGGER.debug("Fixed Vcalendar body to server:\n" + resultString);
                 dumpICS(resultString, false, true);
             }
         }
 
         protected void dumpICS(String icsBody, boolean fromServer, boolean after) {
             String logFileDirectory = Settings.getLogFileDirectory();
 
             // additional setting to activate ICS dump (not available in GUI)
             int dumpMax = Settings.getIntProperty("davmail.dumpICS");
             if (dumpMax > 0) {
                 if (dumpIndex > dumpMax) {
                     // Delete the oldest dump file
                     final int oldest = dumpIndex - dumpMax;
                     try {
                         File[] oldestFiles = (new File(logFileDirectory)).listFiles((dir, name) -> {
                             if (name.endsWith(".ics")) {
                                 int dashIndex = name.indexOf('-');
                                 if (dashIndex > 0) {
                                     try {
                                         int fileIndex = Integer.parseInt(name.substring(0, dashIndex));
                                         return fileIndex < oldest;
                                     } catch (NumberFormatException nfe) {
                                         // ignore
                                     }
                                 }
                             }
                             return false;
                         });
                         if (oldestFiles != null) {
                             for (File file : oldestFiles) {
                                 if (!file.delete()) {
                                     LOGGER.warn("Unable to delete " + file.getAbsolutePath());
                                 }
                             }
                         }
                     } catch (Exception ex) {
                         LOGGER.warn("Error deleting ics dump: " + ex.getMessage());
                     }
                 }
 
                 StringBuilder filePath = new StringBuilder();
                 filePath.append(logFileDirectory).append('/')
                         .append(dumpIndex)
                         .append(after ? "-to" : "-from")
                         .append((after ^ fromServer) ? "-server" : "-client")
                         .append(".ics");
                 if ((icsBody != null) && (!icsBody.isEmpty())) {
                     try (OutputStreamWriter writer = new OutputStreamWriter(Files.newOutputStream(Paths.get(filePath.toString())), StandardCharsets.UTF_8))
                     {
                         writer.write(icsBody);
                     } catch (IOException e) {
                         LOGGER.error(e);
                     }
 
 
                 }
             }
 
         }
 
         /**
          * Build Mime body for event or event message.
          *
          * @return mimeContent as byte array or null
          * @throws IOException on error
          */
         public byte[] createMimeContent() throws IOException {
             String boundary = UUID.randomUUID().toString();
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             MimeOutputStreamWriter writer = new MimeOutputStreamWriter(baos);
 
             writer.writeHeader("Content-Transfer-Encoding", "7bit");
             writer.writeHeader("Content-class", contentClass);
             // append date
             writer.writeHeader("Date", new Date());
 
             // Make sure invites have a proper subject line
             String vEventSubject = vCalendar.getFirstVeventPropertyValue("SUMMARY");
             if (vEventSubject == null) {
                 vEventSubject = BundleMessage.format("MEETING_REQUEST");
             }
 
             // Write a part of the message that contains the
             // ICS description so that invites contain the description text
             String description = vCalendar.getFirstVeventPropertyValue("DESCRIPTION");
 
             // handle notifications
             if ("urn:content-classes:calendarmessage".equals(contentClass)) {
                 // need to parse attendees and organizer to build recipients
                 VCalendar.Recipients recipients = vCalendar.getRecipients(true);
                 String to;
                 String cc;
                 String notificationSubject;
                 if (email.equalsIgnoreCase(recipients.organizer)) {
                     // current user is organizer => notify all
                     to = recipients.attendees;
                     cc = recipients.optionalAttendees;
                     notificationSubject = subject;
                 } else {
                     String status = vCalendar.getAttendeeStatus();
                     // notify only organizer
                     to = recipients.organizer;
                     cc = null;
                     notificationSubject = (status != null) ? (BundleMessage.format(status) + vEventSubject) : subject;
                     description = "";
                 }
 
                 // Allow end user notification edit
                 if (Settings.getBooleanProperty("davmail.caldavEditNotifications")) {
                     // create notification edit dialog
                     NotificationDialog notificationDialog = new NotificationDialog(to,
                             cc, notificationSubject, description);
                     if (!notificationDialog.getSendNotification()) {
                         LOGGER.debug("Notification canceled by user");
                         return null;
                     }
                     // get description from dialog
                     to = notificationDialog.getTo();
                     cc = notificationDialog.getCc();
                     notificationSubject = notificationDialog.getSubject();
                     description = notificationDialog.getBody();
                 }
 
                 // do not send notification if no recipients found
                 if ((to == null || to.isEmpty()) && (cc == null || cc.isEmpty())) {
                     return null;
                 }
 
                 writer.writeHeader("To", to);
                 writer.writeHeader("Cc", cc);
                 writer.writeHeader("Subject", notificationSubject);
 
 
                 if (LOGGER.isDebugEnabled()) {
                     StringBuilder logBuffer = new StringBuilder("Sending notification ");
                     if (to != null) {
                         logBuffer.append("to: ").append(to);
                     }
                     if (cc != null) {
                         logBuffer.append("cc: ").append(cc);
                     }
                     LOGGER.debug(logBuffer.toString());
                 }
             } else {
                 // need to parse attendees and organizer to build recipients
                 VCalendar.Recipients recipients = vCalendar.getRecipients(false);
                 // storing appointment, full recipients header
                 if (recipients.attendees != null) {
                     writer.writeHeader("To", recipients.attendees);
                 } else {
                     // use current user as attendee
                     writer.writeHeader("To", email);
                 }
                 writer.writeHeader("Cc", recipients.optionalAttendees);
 
                 if (recipients.organizer != null) {
                     writer.writeHeader("From", recipients.organizer);
                 } else {
                     writer.writeHeader("From", email);
                 }
             }
             if (vCalendar.getMethod() == null) {
                 vCalendar.setPropertyValue("METHOD", "REQUEST");
             }
             writer.writeHeader("MIME-Version", "1.0");
             writer.writeHeader("Content-Type", "multipart/alternative;\r\n" +
                     "\tboundary=\"----=_NextPart_" + boundary + '\"');
             writer.writeLn();
             writer.writeLn("This is a multi-part message in MIME format.");
             writer.writeLn();
             writer.writeLn("------=_NextPart_" + boundary);
 
             if (description != null && !description.isEmpty()) {
                 writer.writeHeader("Content-Type", "text/plain;\r\n" +
                         "\tcharset=\"utf-8\"");
                 writer.writeHeader("content-transfer-encoding", "8bit");
                 writer.writeLn();
                 writer.flush();
                 baos.write(description.getBytes(StandardCharsets.UTF_8));
                 writer.writeLn();
                 writer.writeLn("------=_NextPart_" + boundary);
             }
             writer.writeHeader("Content-class", contentClass);
             writer.writeHeader("Content-Type", "text/calendar;\r\n" +
                     "\tmethod=" + vCalendar.getMethod() + ";\r\n" +
                     "\tcharset=\"utf-8\""
             );
             writer.writeHeader("Content-Transfer-Encoding", "8bit");
             writer.writeLn();
             writer.flush();
             baos.write(vCalendar.toString().getBytes(StandardCharsets.UTF_8));
             writer.writeLn();
             writer.writeLn("------=_NextPart_" + boundary + "--");
             writer.close();
             return baos.toByteArray();
         }
 
         /**
          * Create or update item
          *
          * @return action result
          * @throws IOException on error
          */
         public abstract ItemResult createOrUpdate() throws IOException;
 
     }
 
     protected abstract Set<String> getItemProperties();
 
     /**
      * Search contacts in provided folder.
      *
      * @param folderPath Exchange folder path
      * @param includeDistList include distribution lists
      * @return list of contacts
      * @throws IOException on error
      */
     public List<ExchangeSession.Contact> getAllContacts(String folderPath, boolean includeDistList) throws IOException {
         return searchContacts(folderPath, ExchangeSession.CONTACT_ATTRIBUTES, isEqualTo("outlookmessageclass", "IPM.Contact"), 0);
     }
 
 
     /**
      * Search contacts in provided folder matching the search query.
      *
      * @param folderPath Exchange folder path
      * @param attributes requested attributes
      * @param condition  Exchange search query
      * @param maxCount   maximum item count
      * @return list of contacts
      * @throws IOException on error
      */
     public abstract List<Contact> searchContacts(String folderPath, Set<String> attributes, Condition condition, int maxCount) throws IOException;
 
     /**
      * Search calendar messages in provided folder.
      *
      * @param folderPath Exchange folder path
      * @return list of calendar messages as Event objects
      * @throws IOException on error
      */
     public abstract List<Event> getEventMessages(String folderPath) throws IOException;
 
     /**
      * Search calendar events in provided folder.
      *
      * @param folderPath Exchange folder path
      * @return list of calendar events
      * @throws IOException on error
      */
     public List<Event> getAllEvents(String folderPath) throws IOException {
         List<Event> results = searchEvents(folderPath, getCalendarItemCondition(getPastDelayCondition("dtstart")));
 
         if (!Settings.getBooleanProperty("davmail.caldavDisableTasks", false) && isMainCalendar(folderPath)) {
             // retrieve tasks from main tasks folder
             results.addAll(searchTasksOnly(folderPath));
         }
 
         return results;
     }
 
     protected abstract Condition getCalendarItemCondition(Condition dateCondition);
 
     protected Condition getPastDelayCondition(String attribute) {
         int caldavPastDelay = Settings.getIntProperty("davmail.caldavPastDelay");
         Condition dateCondition = null;
         if (caldavPastDelay != 0) {
             Calendar cal = Calendar.getInstance();
             cal.add(Calendar.DAY_OF_MONTH, -caldavPastDelay);
             dateCondition = gt(attribute, formatSearchDate(cal.getTime()));
         }
         return dateCondition;
     }
 
     protected Condition getRangeCondition(String timeRangeStart, String timeRangeEnd) throws IOException {
         try {
             SimpleDateFormat parser = getZuluDateFormat();
             ExchangeSession.MultiCondition andCondition = and();
             if (timeRangeStart != null) {
                 andCondition.add(gt("dtend", formatSearchDate(parser.parse(timeRangeStart))));
             }
             if (timeRangeEnd != null) {
                 andCondition.add(lt("dtstart", formatSearchDate(parser.parse(timeRangeEnd))));
             }
             return andCondition;
         } catch (ParseException e) {
             throw new IOException(e + " " + e.getMessage());
         }
     }
 
     /**
      * Search events between start and end.
      *
      * @param folderPath     Exchange folder path
      * @param timeRangeStart date range start in zulu format
      * @param timeRangeEnd   date range start in zulu format
      * @return list of calendar events
      * @throws IOException on error
      */
     public List<Event> searchEvents(String folderPath, String timeRangeStart, String timeRangeEnd) throws IOException {
         Condition dateCondition = getRangeCondition(timeRangeStart, timeRangeEnd);
         Condition condition = getCalendarItemCondition(dateCondition);
 
         return searchEvents(folderPath, condition);
     }
 
     /**
      * Search events between start and end, exclude tasks.
      *
      * @param folderPath     Exchange folder path
      * @param timeRangeStart date range start in zulu format
      * @param timeRangeEnd   date range start in zulu format
      * @return list of calendar events
      * @throws IOException on error
      */
     public List<Event> searchEventsOnly(String folderPath, String timeRangeStart, String timeRangeEnd) throws IOException {
         Condition dateCondition = getRangeCondition(timeRangeStart, timeRangeEnd);
         return searchEvents(folderPath, getCalendarItemCondition(dateCondition));
     }
 
     /**
      * Search tasks only (VTODO).
      *
      * @param folderPath Exchange folder path
      * @return list of tasks
      * @throws IOException on error
      */
     public List<Event> searchTasksOnly(String folderPath) throws IOException {
         // can be called with vTodoOnly condition on default calendar
         String taskFolderPath = folderPath;
         if (isMainCalendar(folderPath)) {
             taskFolderPath = TASKS;
         }
         return searchEvents(taskFolderPath, and(isEqualTo("outlookmessageclass", "IPM.Task"),
                 or(isNull("datecompleted"), getPastDelayCondition("datecompleted"))));
     }
 
     /**
      * Search calendar events in the provided folder.
      *
      * @param folderPath Exchange folder path
      * @param filter     search filter
      * @return list of calendar events
      * @throws IOException on error
      */
     public List<Event> searchEvents(String folderPath, Condition filter) throws IOException {
 
         Condition privateCondition = null;
         if (isSharedFolder(folderPath) && Settings.getBooleanProperty("davmail.excludePrivateEvents", true)) {
             LOGGER.debug("Shared or public calendar: exclude private events");
             privateCondition = isEqualTo("sensitivity", 0);
         }
 
         return searchEvents(folderPath, getItemProperties(),
                 and(filter, privateCondition));
     }
 
     /**
      * Search calendar events or messages in provided folder matching the search query.
      *
      * @param folderPath Exchange folder path
      * @param attributes requested attributes
      * @param condition  Exchange search query
      * @return list of calendar messages as Event objects
      * @throws IOException on error
      */
     public abstract List<Event> searchEvents(String folderPath, Set<String> attributes, Condition condition) throws IOException;
 
     /**
      * convert vcf extension to EML.
      *
      * @param itemName item name
      * @return EML item name
      */
     protected String convertItemNameToEML(String itemName) {
         if (itemName.endsWith(".vcf")) {
             return itemName.substring(0, itemName.length() - 3) + "EML";
         } else {
             return itemName;
         }
     }
 
     /**
      * Get item named eventName in folder
      *
      * @param folderPath Exchange folder path
      * @param itemName   event name
      * @return event object
      * @throws IOException on error
      */
     public abstract Item getItem(String folderPath, String itemName) throws IOException;
 
     /**
      * Contact picture
      */
     public static class ContactPhoto {
         /**
          * Contact picture content type (always image/jpeg on read)
          */
         public String contentType;
         /**
          * Base64 encoded picture content
          */
         public String content;
     }
 
     /**
      * Retrieve contact photo attached to contact
      *
      * @param contact address book contact
      * @return contact photo
      * @throws IOException on error
      */
     public abstract ContactPhoto getContactPhoto(Contact contact) throws IOException;
 
     /**
      * Retrieve contact photo from AD
      *
      * @param email address book contact
      * @return contact photo
      */
     public ContactPhoto getADPhoto(String email) {
         return null;
     }
 
     /**
      * Delete event named itemName in folder
      *
      * @param folderPath Exchange folder path
      * @param itemName   item name
      * @throws IOException on error
      */
     public abstract void deleteItem(String folderPath, String itemName) throws IOException;
 
     /**
      * Mark event processed named eventName in folder
      *
      * @param folderPath Exchange folder path
      * @param itemName   item name
      * @throws IOException on error
      */
     public abstract void processItem(String folderPath, String itemName) throws IOException;
 
 
     private static int dumpIndex;
 
     /**
      * Event result object to hold HTTP status and event etag from an event creation/update.
      */
     public static class ItemResult {
         /**
          * HTTP status
          */
         public int status;
         /**
          * Event etag from response HTTP header
          */
         public String etag;
         /**
          * Created item name
          */
         public String itemName;
     }
 
     /**
      * Build and send the MIME message for the provided ICS event.
      *
      * @param icsBody event in iCalendar format
      * @return HTTP status
      * @throws IOException on error
      */
     public abstract int sendEvent(String icsBody) throws IOException;
 
     /**
      * Create or update item (event or contact) on the Exchange server
      *
      * @param folderPath Exchange folder path
      * @param itemName   event name
      * @param itemBody   event body in iCalendar format
      * @param etag       previous event etag to detect concurrent updates
      * @param noneMatch  if-none-match header value
      * @return HTTP response event result (status and etag)
      * @throws IOException on error
      */
     public ItemResult createOrUpdateItem(String folderPath, String itemName, String itemBody, String etag, String noneMatch) throws IOException {
         if (itemBody.startsWith("BEGIN:VCALENDAR")) {
             if (Settings.getBooleanProperty("davmail.caldavReadonly", false)) {
                 throw new HttpForbiddenException("Calendar is read-only");
             }
             return internalCreateOrUpdateEvent(folderPath, itemName, "urn:content-classes:appointment", itemBody, etag, noneMatch);
         } else if (itemBody.startsWith("BEGIN:VCARD")) {
             return createOrUpdateContact(folderPath, itemName, itemBody, etag, noneMatch);
         } else {
             throw new IOException(BundleMessage.format("EXCEPTION_INVALID_MESSAGE_CONTENT", itemBody));
         }
     }
 
     static final String[] VCARD_N_PROPERTIES = {"sn", "givenName", "middlename", "personaltitle", "namesuffix"};
     static final String[] VCARD_ADR_HOME_PROPERTIES = {"homepostofficebox", null, "homeStreet", "homeCity", "homeState", "homePostalCode", "homeCountry"};
     static final String[] VCARD_ADR_WORK_PROPERTIES = {"postofficebox", "roomnumber", "street", "l", "st", "postalcode", "co"};
     static final String[] VCARD_ADR_OTHER_PROPERTIES = {"otherpostofficebox", null, "otherstreet", "othercity", "otherstate", "otherpostalcode", "othercountry"};
     static final String[] VCARD_ORG_PROPERTIES = {"o", "department"};
 
     protected void convertContactProperties(Map<String, String> properties, String[] contactProperties, List<String> values) {
         for (int i = 0; i < values.size() && i < contactProperties.length; i++) {
             if (contactProperties[i] != null) {
                 properties.put(contactProperties[i], values.get(i));
             }
         }
     }
 
     protected ItemResult createOrUpdateContact(String folderPath, String itemName, String itemBody, String etag, String noneMatch) throws IOException {
         // parse VCARD body to build contact property map
         Map<String, String> properties = new HashMap<>();
 
         VObject vcard = new VObject(new ICSBufferedReader(new StringReader(itemBody)));
         if ("group".equalsIgnoreCase(vcard.getPropertyValue("KIND"))) {
             properties.put("outlookmessageclass", "IPM.DistList");
             properties.put("displayname", vcard.getPropertyValue("FN"));
             properties.put("personalNotes", vcard.getPropertyValue("NOTE"));
         } else {
             properties.put("outlookmessageclass", "IPM.Contact");
 
             for (VProperty property : vcard.getProperties()) {
                 if ("FN".equals(property.getKey())) {
                     properties.put("cn", property.getValue());
                     properties.put("subject", property.getValue());
                     properties.put("fileas", property.getValue());
 
                 } else if ("N".equals(property.getKey())) {
                     convertContactProperties(properties, VCARD_N_PROPERTIES, property.getValues());
                 } else if ("NICKNAME".equals(property.getKey())) {
                     properties.put("nickname", property.getValue());
                 } else if ("TEL".equals(property.getKey())) {
                     if (property.hasParam("TYPE", "cell") || property.hasParam("X-GROUP", "cell")) {
                         properties.put("mobile", property.getValue());
                     } else if (property.hasParam("TYPE", "work") || property.hasParam("X-GROUP", "work")) {
                         if (properties.containsKey("telephoneNumber")) {
                             if (properties.containsKey("otherBusinessTelephoneNumber")) {
                                 LOGGER.warn("Ignore third work phone  " + property.getValue());
                             } else {
                                 // secondary business phone
                                 properties.put("otherBusinessTelephoneNumber", property.getValue());
                             }
                         } else {
                             properties.put("telephoneNumber", property.getValue());
                         }
                     } else if (property.hasParam("TYPE", "home") || property.hasParam("X-GROUP", "home")) {
                         if (properties.containsKey("homePhone")) {
                             if (properties.containsKey("otherHomePhone")) {
                                 LOGGER.warn("Ignore third home phone  " + property.getValue());
                             } else {
                                 // secondary home phone
                                 properties.put("otherHomePhone", property.getValue());
                             }
                         } else {
                             properties.put("homePhone", property.getValue());
                         }
 
                     } else if (property.hasParam("TYPE", "fax")) {
                         if (property.hasParam("TYPE", "home")) {
                             properties.put("homefax", property.getValue());
                         } else {
                             properties.put("facsimiletelephonenumber", property.getValue());
                         }
                     } else if (property.hasParam("TYPE", "pager")) {
                         properties.put("pager", property.getValue());
                     } else if (property.hasParam("TYPE", "car")) {
                         properties.put("othermobile", property.getValue());
                     } else {
                         properties.put("otherTelephone", property.getValue());
                     }
                 } else if ("ADR".equals(property.getKey())) {
                     // address
                     if (property.hasParam("TYPE", "home")) {
                         convertContactProperties(properties, VCARD_ADR_HOME_PROPERTIES, property.getValues());
                     } else if (property.hasParam("TYPE", "work")) {
                         convertContactProperties(properties, VCARD_ADR_WORK_PROPERTIES, property.getValues());
                         // any other type goes to other address
                     } else {
                         convertContactProperties(properties, VCARD_ADR_OTHER_PROPERTIES, property.getValues());
                     }
                 } else if ("EMAIL".equals(property.getKey())) {
                     if (property.hasParam("TYPE", "home")) {
                         properties.put("email2", property.getValue());
                         properties.put("smtpemail2", property.getValue());
                     } else if (property.hasParam("TYPE", "other")) {
                         properties.put("email3", property.getValue());
                         properties.put("smtpemail3", property.getValue());
                     } else {
                         properties.put("email1", property.getValue());
                         properties.put("smtpemail1", property.getValue());
                     }
                 } else if ("ORG".equals(property.getKey())) {
                     convertContactProperties(properties, VCARD_ORG_PROPERTIES, property.getValues());
                 } else if ("URL".equals(property.getKey())) {
                     if (property.hasParam("TYPE", "work")) {
                         properties.put("businesshomepage", property.getValue());
                     } else if (property.hasParam("TYPE", "home")) {
                         properties.put("personalHomePage", property.getValue());
                     } else {
                         // default: set personal home page
                         properties.put("personalHomePage", property.getValue());
                     }
                 } else if ("TITLE".equals(property.getKey())) {
                     properties.put("title", property.getValue());
                 } else if ("NOTE".equals(property.getKey())) {
                     properties.put("personalNotes", property.getValue());
                 } else if ("CUSTOM1".equals(property.getKey())) {
                     properties.put("extensionattribute1", property.getValue());
                 } else if ("CUSTOM2".equals(property.getKey())) {
                     properties.put("extensionattribute2", property.getValue());
                 } else if ("CUSTOM3".equals(property.getKey())) {
                     properties.put("extensionattribute3", property.getValue());
                 } else if ("CUSTOM4".equals(property.getKey())) {
                     properties.put("extensionattribute4", property.getValue());
                 } else if ("ROLE".equals(property.getKey())) {
                     properties.put("profession", property.getValue());
                 } else if ("X-AIM".equals(property.getKey())) {
                     properties.put("im", property.getValue());
                 } else if ("BDAY".equals(property.getKey())) {
                     properties.put("bday", convertBDayToZulu(property.getValue()));
                 } else if ("ANNIVERSARY".equals(property.getKey()) || "X-ANNIVERSARY".equals(property.getKey())) {
                     properties.put("anniversary", convertBDayToZulu(property.getValue()));
                 } else if ("CATEGORIES".equals(property.getKey())) {
                     properties.put("keywords", property.getValue());
                 } else if ("CLASS".equals(property.getKey())) {
                     if ("PUBLIC".equals(property.getValue())) {
                         properties.put("sensitivity", "0");
                         properties.put("private", "false");
                     } else {
                         properties.put("sensitivity", "2");
                         properties.put("private", "true");
                     }
                 } else if ("SEX".equals(property.getKey())) {
                     String propertyValue = property.getValue();
                     if ("1".equals(propertyValue)) {
                         properties.put("gender", "2");
                     } else if ("2".equals(propertyValue)) {
                         properties.put("gender", "1");
                     }
                 } else if ("FBURL".equals(property.getKey())) {
                     properties.put("fburl", property.getValue());
                 } else if ("X-ASSISTANT".equals(property.getKey())) {
                     properties.put("secretarycn", property.getValue());
                 } else if ("X-MANAGER".equals(property.getKey())) {
                     properties.put("manager", property.getValue());
                 } else if ("X-SPOUSE".equals(property.getKey())) {
                     properties.put("spousecn", property.getValue());
                 } else if ("PHOTO".equals(property.getKey())) {
                     String value = property.getValue();
                     if ("data:image/jpeg".equals(value) && property.values.size() > 1) {
                         value = property.getValues().get(1);
                         if (value.startsWith("base64,")) {
                             value = value.substring(7);
                         }
                     }
                     properties.put("photo", value);
                     properties.put("haspicture", "true");
                 } else if ("KEY1".equals(property.getKey())) {
                     properties.put("msexchangecertificate", property.getValue());
                 } else if ("KEY2".equals(property.getKey())) {
                     properties.put("usersmimecertificate", property.getValue());
                 }
             }
             LOGGER.debug("Create or update contact " + itemName + ": " + properties);
             // reset missing properties to null
             for (String key : CONTACT_ATTRIBUTES) {
                 if (!"imapUid".equals(key) && !"etag".equals(key) && !"urlcompname".equals(key) && !"uid".equals(key)
                         && !"lastmodified".equals(key) && !"sensitivity".equals(key)
                         && !"haspicture".equals(key)
                         && !"usersmimecertificate".equals(key) && !"msexchangecertificate".equals(key)
                         && !properties.containsKey(key)) {
                     properties.put(key, null);
                 }
             }
         }
 
         Contact contact = buildContact(folderPath, itemName, properties, etag, noneMatch);
         for (VProperty property : vcard.getProperties()) {
             if ("MEMBER".equals(property.getKey())) {
                 String member = property.getValue();
                 if (member.startsWith("urn:uuid:")) {
                     Item item = getItem(folderPath, member.substring(9) + ".EML");
                     if (item != null) {
                         if (item.get("smtpemail1") != null) {
                             member = "mailto:" + item.get("smtpemail1");
                         } else if (item.get("smtpemail2") != null) {
                             member = "mailto:" + item.get("smtpemail2");
                         } else if (item.get("smtpemail3") != null) {
                             member = "mailto:" + item.get("smtpemail3");
                         }
                     }
                 }
                 contact.addMember(member);
             }
         }
         return contact.createOrUpdate();
     }
 
     protected String convertZuluDateToBday(String value) {
         String result = null;
         if (value != null && !value.isEmpty()) {
             try {
                 SimpleDateFormat parser = ExchangeSession.getZuluDateFormat();
                 Calendar cal = Calendar.getInstance();
                 cal.setTime(parser.parse(value));
                 cal.add(Calendar.HOUR_OF_DAY, 12);
                 result = ExchangeSession.getVcardBdayFormat().format(cal.getTime());
             } catch (ParseException e) {
                 LOGGER.warn("Invalid date: " + value);
             }
         }
         return result;
     }
 
     protected String convertBDayToZulu(String value) {
         String result = null;
         if (value != null && !value.isEmpty()) {
             try {
                 SimpleDateFormat parser;
                 if (value.length() == 8) {
                     parser = new SimpleDateFormat("yyyyMMdd", Locale.ENGLISH);
                     parser.setTimeZone(GMT_TIMEZONE);
                 } else if (value.length() == 10) {
                     parser = ExchangeSession.getVcardBdayFormat();
                 } else if (value.length() == 15) {
                     parser = new SimpleDateFormat("yyyyMMdd'T'HHmmss", Locale.ENGLISH);
                     parser.setTimeZone(GMT_TIMEZONE);
                 } else {
                     parser = ExchangeSession.getExchangeZuluDateFormat();
                 }
                 result = ExchangeSession.getExchangeZuluDateFormatMillisecond().format(parser.parse(value));
             } catch (ParseException e) {
                 LOGGER.warn("Invalid date: " + value);
             }
         }
 
         return result;
     }
 
 
     protected abstract Contact buildContact(String folderPath, String itemName, Map<String, String> properties, String etag, String noneMatch) throws IOException;
 
     protected abstract ItemResult internalCreateOrUpdateEvent(String folderPath, String itemName, String contentClass, String icsBody, String etag, String noneMatch) throws IOException;
 
     /**
      * Get current Exchange alias name from login name
      *
      * @return user name
      */
     public String getAliasFromLogin() {
         // login is email, not alias
         if (this.userName.indexOf('@') >= 0) {
             return null;
         }
         String result = this.userName;
         // remove domain name
         int index = Math.max(result.indexOf('\\'), result.indexOf('/'));
         if (index >= 0) {
             result = result.substring(index + 1);
         }
         return result;
     }
 
     /**
      * Test if folderPath is inside user mailbox.
      *
      * @param folderPath absolute folder path
      * @return true if folderPath is a public or shared folder
      */
     public abstract boolean isSharedFolder(String folderPath);
 
     /**
      * Test if folderPath is main calendar.
      *
      * @param folderPath absolute folder path
      * @return true if folderPath is a public or shared folder
      */
     public abstract boolean isMainCalendar(String folderPath) throws IOException;
 
     protected static final String MAILBOX_BASE = "/cn=";
 
     /**
      * Get current user email
      *
      * @return user email
      */
     public String getEmail() {
         return email;
     }
 
     /**
      * Get email from current calendar
      * @param folderPath calendar folder path
      * @return calendar mailbox
      */
     protected abstract String getCalendarEmail(String folderPath) throws IOException;
 
     /**
      * Get current user alias
      *
      * @return user email
      */
     public String getAlias() {
         return alias;
     }
 
     /**
      * Search global address list
      *
      * @param condition           search filter
      * @param returningAttributes returning attributes
      * @param sizeLimit           size limit
      * @return matching contacts from gal
      * @throws IOException on error
      */
     public abstract Map<String, Contact> galFind(Condition condition, Set<String> returningAttributes, int sizeLimit) throws IOException;
 
     /**
      * Full Contact attribute list
      */
     public static final Set<String> CONTACT_ATTRIBUTES = new HashSet<>();
 
     static {
         CONTACT_ATTRIBUTES.add("uid");
         CONTACT_ATTRIBUTES.add("imapUid");
         CONTACT_ATTRIBUTES.add("etag");
         CONTACT_ATTRIBUTES.add("urlcompname");
 
         CONTACT_ATTRIBUTES.add("extensionattribute1");
         CONTACT_ATTRIBUTES.add("extensionattribute2");
         CONTACT_ATTRIBUTES.add("extensionattribute3");
         CONTACT_ATTRIBUTES.add("extensionattribute4");
         CONTACT_ATTRIBUTES.add("bday");
         CONTACT_ATTRIBUTES.add("anniversary");
         CONTACT_ATTRIBUTES.add("businesshomepage");
         CONTACT_ATTRIBUTES.add("personalHomePage");
         CONTACT_ATTRIBUTES.add("cn");
         CONTACT_ATTRIBUTES.add("co");
         CONTACT_ATTRIBUTES.add("department");
         CONTACT_ATTRIBUTES.add("smtpemail1");
         CONTACT_ATTRIBUTES.add("smtpemail2");
         CONTACT_ATTRIBUTES.add("smtpemail3");
         CONTACT_ATTRIBUTES.add("facsimiletelephonenumber");
         CONTACT_ATTRIBUTES.add("givenName");
         CONTACT_ATTRIBUTES.add("internationalisdnnumber");
         CONTACT_ATTRIBUTES.add("homeCity");
         CONTACT_ATTRIBUTES.add("homeCountry");
         CONTACT_ATTRIBUTES.add("homefax");
         CONTACT_ATTRIBUTES.add("homePhone");
         CONTACT_ATTRIBUTES.add("homePostalCode");
         CONTACT_ATTRIBUTES.add("homeState");
         CONTACT_ATTRIBUTES.add("homeStreet");
         CONTACT_ATTRIBUTES.add("homepostofficebox");
         CONTACT_ATTRIBUTES.add("l");
         CONTACT_ATTRIBUTES.add("manager");
         CONTACT_ATTRIBUTES.add("mobile");
         CONTACT_ATTRIBUTES.add("namesuffix");
         CONTACT_ATTRIBUTES.add("nickname");
         CONTACT_ATTRIBUTES.add("o");
         CONTACT_ATTRIBUTES.add("pager");
         CONTACT_ATTRIBUTES.add("personaltitle");
         CONTACT_ATTRIBUTES.add("postalcode");
         CONTACT_ATTRIBUTES.add("postofficebox");
         CONTACT_ATTRIBUTES.add("profession");
         CONTACT_ATTRIBUTES.add("roomnumber");
         CONTACT_ATTRIBUTES.add("secretarycn");
         CONTACT_ATTRIBUTES.add("sn");
         CONTACT_ATTRIBUTES.add("spousecn");
         CONTACT_ATTRIBUTES.add("st");
         CONTACT_ATTRIBUTES.add("street");
         CONTACT_ATTRIBUTES.add("telephoneNumber");
         CONTACT_ATTRIBUTES.add("title");
         CONTACT_ATTRIBUTES.add("description");
         CONTACT_ATTRIBUTES.add("personalNotes");
         CONTACT_ATTRIBUTES.add("im");
         CONTACT_ATTRIBUTES.add("middlename");
         CONTACT_ATTRIBUTES.add("lastmodified");
         CONTACT_ATTRIBUTES.add("otherstreet");
         CONTACT_ATTRIBUTES.add("otherstate");
         CONTACT_ATTRIBUTES.add("otherpostofficebox");
         CONTACT_ATTRIBUTES.add("otherpostalcode");
         CONTACT_ATTRIBUTES.add("othercountry");
         CONTACT_ATTRIBUTES.add("othercity");
         CONTACT_ATTRIBUTES.add("haspicture");
         CONTACT_ATTRIBUTES.add("keywords");
         CONTACT_ATTRIBUTES.add("othermobile");
         CONTACT_ATTRIBUTES.add("otherBusinessTelephoneNumber");
         CONTACT_ATTRIBUTES.add("otherHomePhone");
         CONTACT_ATTRIBUTES.add("otherTelephone");
         CONTACT_ATTRIBUTES.add("gender");
         CONTACT_ATTRIBUTES.add("private");
         CONTACT_ATTRIBUTES.add("sensitivity");
         CONTACT_ATTRIBUTES.add("fburl");
         CONTACT_ATTRIBUTES.add("msexchangecertificate");
         CONTACT_ATTRIBUTES.add("usersmimecertificate");
     }
 
     protected static final Set<String> DISTRIBUTION_LIST_ATTRIBUTES = new HashSet<>();
 
     static {
         DISTRIBUTION_LIST_ATTRIBUTES.add("imapUid");
         DISTRIBUTION_LIST_ATTRIBUTES.add("etag");
         DISTRIBUTION_LIST_ATTRIBUTES.add("urlcompname");
 
         DISTRIBUTION_LIST_ATTRIBUTES.add("cn");
         DISTRIBUTION_LIST_ATTRIBUTES.add("members");
     }
 
     /**
      * Get freebusy data string from Exchange.
      *
      * @param attendee attendee email address
      * @param start    start date in Exchange zulu format
      * @param end      end date in Exchange zulu format
      * @param interval freebusy interval in minutes
      * @return freebusy data or null
      * @throws IOException on error
      */
     protected abstract String getFreeBusyData(String attendee, String start, String end, int interval) throws IOException;
 
     /**
      * Get freebusy info for attendee between start and end date.
      *
      * @param attendee       attendee email
      * @param startDateValue start date
      * @param endDateValue   end date
      * @return FreeBusy info
      * @throws IOException on error
      */
     public FreeBusy getFreebusy(String attendee, String startDateValue, String endDateValue) throws IOException {
         // replace ical encoded attendee name
         attendee = VCalendar.replaceIcal4Principal(attendee);
 
         // then check that email address is valid to avoid InvalidSmtpAddress error
         if (attendee == null || attendee.indexOf('@') < 0 || attendee.charAt(attendee.length() - 1) == '@') {
             return null;
         }
 
         if (attendee.startsWith("mailto:") || attendee.startsWith("MAILTO:")) {
             attendee = attendee.substring("mailto:".length());
         }
 
         SimpleDateFormat exchangeZuluDateFormat = getExchangeZuluDateFormat();
         SimpleDateFormat icalDateFormat = getZuluDateFormat();
 
         Date startDate;
         Date endDate;
         try {
             if (startDateValue.length() == 8) {
                 startDate = parseDate(startDateValue);
             } else {
                 startDate = icalDateFormat.parse(startDateValue);
             }
             if (endDateValue.length() == 8) {
                 endDate = parseDate(endDateValue);
             } else {
                 endDate = icalDateFormat.parse(endDateValue);
             }
         } catch (ParseException e) {
             throw new DavMailException("EXCEPTION_INVALID_DATES", e.getMessage());
         }
 
         FreeBusy freeBusy = null;
         String fbdata = getFreeBusyData(attendee, exchangeZuluDateFormat.format(startDate), exchangeZuluDateFormat.format(endDate), FREE_BUSY_INTERVAL);
         if (fbdata != null) {
             freeBusy = new FreeBusy(icalDateFormat, startDate, fbdata);
         }
 
         if (freeBusy != null && freeBusy.knownAttendee) {
             return freeBusy;
         } else {
             return null;
         }
     }
 
     /**
      * Exchange to iCalendar Free/Busy parser.
      * Free time returns 0, Tentative returns 1, Busy returns 2, and Out of Office (OOF) returns 3
      */
     public static final class FreeBusy {
         final SimpleDateFormat icalParser;
         boolean knownAttendee = true;
         static final HashMap<Character, String> FBTYPES = new HashMap<>();
 
         static {
             FBTYPES.put('1', "BUSY-TENTATIVE");
             FBTYPES.put('2', "BUSY");
             FBTYPES.put('3', "BUSY-UNAVAILABLE");
         }
 
         final HashMap<String, StringBuilder> busyMap = new HashMap<>();
 
         StringBuilder getBusyBuffer(char type) {
             String fbType = FBTYPES.get(type);
             return busyMap.computeIfAbsent(fbType, k -> new StringBuilder());
         }
 
         void startBusy(char type, Calendar currentCal) {
             if (type == '4') {
                 knownAttendee = false;
             } else if (type != '0') {
                 StringBuilder busyBuffer = getBusyBuffer(type);
                 if (busyBuffer.length() > 0) {
                     busyBuffer.append(',');
                 }
                 busyBuffer.append(icalParser.format(currentCal.getTime()));
             }
         }
 
         void endBusy(char type, Calendar currentCal) {
             if (type != '0' && type != '4') {
                 getBusyBuffer(type).append('/').append(icalParser.format(currentCal.getTime()));
             }
         }
 
         FreeBusy(SimpleDateFormat icalParser, Date startDate, String fbdata) {
             this.icalParser = icalParser;
             if (!fbdata.isEmpty()) {
                 Calendar currentCal = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
                 currentCal.setTime(startDate);
 
                 startBusy(fbdata.charAt(0), currentCal);
                 for (int i = 1; i < fbdata.length() && knownAttendee; i++) {
                     currentCal.add(Calendar.MINUTE, FREE_BUSY_INTERVAL);
                     char previousState = fbdata.charAt(i - 1);
                     char currentState = fbdata.charAt(i);
                     if (previousState != currentState) {
                         endBusy(previousState, currentCal);
                         startBusy(currentState, currentCal);
                     }
                 }
                 currentCal.add(Calendar.MINUTE, FREE_BUSY_INTERVAL);
                 endBusy(fbdata.charAt(fbdata.length() - 1), currentCal);
             }
         }
 
         /**
          * Append freebusy information to provided buffer.
          *
          * @param buffer String buffer
          */
         public void appendTo(StringBuilder buffer) {
             for (Map.Entry<String, StringBuilder> entry : busyMap.entrySet()) {
                 buffer.append("FREEBUSY;FBTYPE=").append(entry.getKey())
                         .append(':').append(entry.getValue()).append((char) 13).append((char) 10);
             }
         }
     }
 
     protected VObject vTimezone;
 
     /**
      * Load and return current user OWA timezone.
      *
      * @return current timezone
      */
     public VObject getVTimezone() {
         if (vTimezone == null) {
             // need to load Timezone info from OWA
             loadVtimezone();
         }
         return vTimezone;
     }
 
     public String getTimezoneId() {
         return getVTimezone().getPropertyValue("TZID");
     }
 
     public void clearVTimezone() {
         vTimezone = null;
     }
 
     protected abstract void loadVtimezone();
 
     protected static final Map<String, String> importanceToPriorityMap = new HashMap<>();
 
     static {
         importanceToPriorityMap.put("High", "1");
         importanceToPriorityMap.put("Normal", "5");
         importanceToPriorityMap.put("Low", "9");
     }
 
     protected static final Map<String, String> priorityToImportanceMap = new HashMap<>();
 
     static {
         // 0 means undefined, map it to normal
         priorityToImportanceMap.put("0", "Normal");
 
         priorityToImportanceMap.put("1", "High");
         priorityToImportanceMap.put("2", "High");
         priorityToImportanceMap.put("3", "High");
         priorityToImportanceMap.put("4", "Normal");
         priorityToImportanceMap.put("5", "Normal");
         priorityToImportanceMap.put("6", "Normal");
         priorityToImportanceMap.put("7", "Low");
         priorityToImportanceMap.put("8", "Low");
         priorityToImportanceMap.put("9", "Low");
     }
 
     protected String convertPriorityFromExchange(String exchangeImportanceValue) {
         String value = null;
         if (exchangeImportanceValue != null) {
             value = importanceToPriorityMap.get(exchangeImportanceValue);
         }
         return value;
     }
 
     protected String convertPriorityToExchange(String vTodoPriorityValue) {
         String value = null;
         if (vTodoPriorityValue != null) {
             value = priorityToImportanceMap.get(vTodoPriorityValue);
         }
         return value;
     }
 
     /**
      * Possible values are: normal, personal, private, and confidential.
      * @param sensitivity Exchange sensitivity
      * @return event class
      */
     protected String convertClassFromExchange(String sensitivity) {
         String eventClass;
         if ("private".equals(sensitivity)) {
             eventClass = "PRIVATE";
         } else if ("confidential".equals(sensitivity)) {
             eventClass = "CONFIDENTIAL";
         } else if ("personal".equals(sensitivity)) {
             eventClass = "PRIVATE";
         } else {
             // normal
             eventClass = "PUBLIC";
         }
         return eventClass;
     }
 
 }