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 *  Upgrade UW-IMAP to Panda IMAP from https://github.com/jonabbey/panda-imap.
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+Network Working Group                                        A. Melnikov
+Request for Comments: 5162                                   D. Cridland
+Category: Standards Track                                      Isode Ltd
+                                                               C. Wilson
+                                                                   Nokia
+                                                              March 2008
+
+
+          IMAP4 Extensions for Quick Mailbox Resynchronization
+
+Status of This Memo
+
+   This document specifies an Internet standards track protocol for the
+   Internet community, and requests discussion and suggestions for
+   improvements.  Please refer to the current edition of the "Internet
+   Official Protocol Standards" (STD 1) for the standardization state
+   and status of this protocol.  Distribution of this memo is unlimited.
+
+Abstract
+
+   This document defines an IMAP4 extension, which gives an IMAP client
+   the ability to quickly resynchronize any previously opened mailbox as
+   part of the SELECT command, without the need for server-side state or
+   additional client round-trips.  This extension also introduces a new
+   response that allows for a more compact representation of a list of
+   expunged messages (and always includes the Unique Identifiers (UIDs)
+   expunged).
+
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+Melnikov, et al.            Standards Track                     [Page 1]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+Table of Contents
+
+   1.  Introduction and Overview  . . . . . . . . . . . . . . . . . .  2
+   2.  Requirements Notation  . . . . . . . . . . . . . . . . . . . .  4
+   3.  IMAP Protocol Changes  . . . . . . . . . . . . . . . . . . . .  4
+     3.1.  QRESYNC Parameter to SELECT/EXAMINE  . . . . . . . . . . .  4
+     3.2.  VANISHED UID FETCH Modifier  . . . . . . . . . . . . . . .  8
+     3.3.  EXPUNGE Command  . . . . . . . . . . . . . . . . . . . . . 10
+     3.4.  CLOSE Command  . . . . . . . . . . . . . . . . . . . . . . 11
+     3.5.  UID EXPUNGE Command  . . . . . . . . . . . . . . . . . . . 11
+     3.6.  VANISHED Response  . . . . . . . . . . . . . . . . . . . . 12
+     3.7.  CLOSED Response Code . . . . . . . . . . . . . . . . . . . 15
+   4.  Server Implementation Considerations . . . . . . . . . . . . . 15
+     4.1.  Server Implementations That Don't Store Extra State  . . . 15
+     4.2.  Server Implementations Storing Minimal State . . . . . . . 16
+     4.3.  Additional State Required on the Server  . . . . . . . . . 16
+   5.  Updated Synchronization Sequence . . . . . . . . . . . . . . . 17
+   6.  Formal Syntax  . . . . . . . . . . . . . . . . . . . . . . . . 19
+   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
+   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 21
+   9.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 21
+   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
+     10.1. Normative References . . . . . . . . . . . . . . . . . . . 21
+     10.2. Informative References . . . . . . . . . . . . . . . . . . 22
+
+1.  Introduction and Overview
+
+   The [CONDSTORE] extension gives a disconnected client the ability to
+   quickly resynchronize IMAP flag changes for previously seen messages.
+   This can be done using the CHANGEDSINCE FETCH modifier once a mailbox
+   is opened.  In order for the client to discover which messages have
+   been expunged, the client still has to issue a UID FETCH or a UID
+   SEARCH command.  This document defines an extension to [CONDSTORE]
+   that allows a reconnecting client to perform full resynchronization,
+   including discovery of expunged messages, in a single round-trip.
+   This extension also introduces a new response, VANISHED, that allows
+   for a more compact representation of a list of expunged messages.
+
+   This extension can be useful for mobile clients that can experience
+   frequent disconnects caused by environmental factors (battery life,
+   signal strength, etc.).  Such clients need a way to quickly reconnect
+   to the IMAP server, while minimizing delay experienced by the user as
+   well as the amount of traffic (and hence the expense) generated by
+   resynchronization.
+
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                     [Page 2]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   By extending the SELECT command to perform the additional
+   resynchronization, this also allows clients to reduce concurrent
+   connections to the IMAP server held purely for the sake of avoiding
+   the resynchronization.
+
+   The quick resync IMAP extension is present if an IMAP4 server returns
+   "QRESYNC" as one of the supported capabilities to the CAPABILITY
+   command.
+
+   Servers supporting this extension MUST implement and advertise
+   support for the [ENABLE] IMAP extension.  Also, the presence of the
+   "QRESYNC" capability implies support for the [CONDSTORE] IMAP
+   extension even if the CONDSTORE capability isn't advertised.  A
+   server compliant with this specification is REQUIREd to support
+   "ENABLE QRESYNC" and "ENABLE QRESYNC CONDSTORE" (which are "CONDSTORE
+   enabling commands", as defined in [CONDSTORE], and have identical
+   results), but there is no requirement for a compliant server to
+   support "ENABLE CONDSTORE" by itself.  The "ENABLE QRESYNC"/"ENABLE
+   QRESYNC CONDSTORE" command also tells the server that it SHOULD start
+   sending VANISHED responses (see Section 3.6) instead of EXPUNGE
+   responses.  This change remains in effect until the connection is
+   closed.
+
+   For compatibility with clients that only support the [CONDSTORE] IMAP
+   extension, servers SHOULD advertise CONDSTORE in the CAPABILITY
+   response as well.
+
+   A client making use of this extension MUST issue "ENABLE QRESYNC"
+   once it is authenticated.  A server MUST respond with a tagged BAD
+   response if the QRESYNC parameter to the SELECT/EXAMINE command or
+   the VANISHED UID FETCH modifier is specified and the client hasn't
+   issued "ENABLE QRESYNC" in the current connection.
+
+   This document puts additional requirements on a server implementing
+   the [CONDSTORE] extension.  Each mailbox that supports persistent
+   storage of mod-sequences, i.e., for which the server has sent a
+   HIGHESTMODSEQ untagged OK response code on a successful SELECT/
+   EXAMINE, MUST increment the per-mailbox mod-sequence when one or more
+   messages are expunged due to EXPUNGE, UID EXPUNGE or CLOSE; the
+   server MUST associate the incremented mod-sequence with the UIDs of
+   the expunged messages.
+
+   A client that supports CONDSTORE but not this extension might
+   resynchronize a mailbox and discover that its HIGHESTMODSEQ has
+   increased from the value cached by the client.  If the increase is
+   only due to messages having been expunged since the client last
+   synchronized, the client is likely to send a FETCH ...  CHANGEDSINCE
+   command that returns no data.  Thus, a client that supports CONDSTORE
+
+
+
+Melnikov, et al.            Standards Track                     [Page 3]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   but not this extension might incur a penalty of an unneeded round-
+   trip when resynchronizing some mailboxes (those that have had
+   messages expunged but no flag changes since the last
+   synchronization).
+
+   This extra round-trip is only incurred by clients that support
+   CONDSTORE but not this extension, and only when a mailbox has had
+   messages expunged but no flag changes to non-expunged messages.
+   Since CONDSTORE is a relatively new extension, it is thought likely
+   that clients that support it will also support this extension.
+
+2.  Requirements Notation
+
+   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+   document are to be interpreted as described in [RFC2119].
+
+   In examples, "C:" and "S:" indicate lines sent by the client and
+   server respectively.  If a single "C:" or "S:" label applies to
+   multiple lines, then the line breaks between those lines are for
+   editorial clarity only and are not part of the actual protocol
+   exchange.  The five characters [...] means that something has been
+   elided.
+
+   Understanding of the IMAP message sequence numbers and UIDs and the
+   EXPUNGE response [RFC3501] is essential when reading this document.
+
+3.  IMAP Protocol Changes
+
+3.1.  QRESYNC Parameter to SELECT/EXAMINE
+
+   The Quick Resynchronization parameter to SELECT/EXAMINE commands has
+   four arguments:
+
+   o  the last known UIDVALIDITY,
+
+   o  the last known modification sequence,
+
+   o  the optional set of known UIDs, and
+
+   o  an optional parenthesized list of known sequence ranges and their
+      corresponding UIDs.
+
+   A server MUST respond with a tagged BAD response if the Quick
+   Resynchronization parameter to SELECT/EXAMINE command is specified
+   and the client hasn't issued "ENABLE QRESYNC" in the current
+   connection.
+
+
+
+
+Melnikov, et al.            Standards Track                     [Page 4]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   Before opening the specified mailbox, the server verifies all
+   arguments for syntactic validity.  If any parameter is not
+   syntactically valid, the server returns the tagged BAD response, and
+   the mailbox remains unselected.  Once the check is done, the server
+   opens the mailbox as if no SELECT/EXAMINE parameters are specified
+   (this is subject to processing of other parameters as defined in
+   other extensions).  In particular this means that the server MUST
+   send all untagged responses as specified in Sections 6.3.1 and 6.3.2
+   of [RFC3501].
+
+   After that, the server checks the UIDVALIDITY value provided by the
+   client.  If the provided UIDVALIDITY doesn't match the UIDVALIDITY
+   for the mailbox being opened, then the server MUST ignore the
+   remaining parameters and behave as if no dynamic message data
+   changed.  The client can discover this situation by comparing the
+   UIDVALIDITY value returned by the server.  This behavior allows the
+   client not to synchronize the mailbox or decide on the best
+   synchronization strategy.
+
+   Example: Attempting to resynchronize INBOX, but the provided
+            UIDVALIDITY parameter doesn't match the current UIDVALIDITY
+            value.
+
+   C: A02 SELECT INBOX (QRESYNC (67890007 20050715194045000
+            41,43:211,214:541))
+            S: * 464 EXISTS
+            S: * 3 RECENT
+            S: * OK [UIDVALIDITY 3857529045] UIDVALIDITY
+            S: * OK [UIDNEXT 550] Predicted next UID
+            S: * OK [HIGHESTMODSEQ 90060128194045007]
+            S: * OK [UNSEEN 12] Message 12 is first unseen
+            S: * FLAGS (\Answered \Flagged \Draft \Deleted \Seen)
+            S: * OK [PERMANENTFLAGS (\Answered \Flagged \Draft
+            \Deleted \Seen \*)] Permanent flags
+            S: A02 OK [READ-WRITE] Sorry, UIDVALIDITY mismatch
+
+   Modification Sequence and UID Parameters:
+
+   A server that doesn't support the persistent storage of mod-sequences
+   for the mailbox MUST send the OK untagged response including the
+   NOMODSEQ response code with every successful SELECT or EXAMINE
+   command, as described in [CONDSTORE].  Such a server doesn't need to
+   remember mod-sequences for expunged messages in the mailbox.  It MUST
+   ignore the remaining parameters and behave as if no dynamic message
+   data changed.
+
+   If the provided UIDVALIDITY matches that of the selected mailbox, the
+   server then checks the last known modification sequence.
+
+
+
+Melnikov, et al.            Standards Track                     [Page 5]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   The server sends the client any pending flag changes (using FETCH
+   responses that MUST contain UIDs) and expunges those that have
+   occurred in this mailbox since the provided modification sequence.
+
+   If the list of known UIDs was also provided, the server should only
+   report flag changes and expunges for the specified messages.  If the
+   client did not provide the list of UIDs, the server acts as if the
+   client has specified "1:<maxuid>", where <maxuid> is the mailbox's
+   UIDNEXT value minus 1.  If the mailbox is empty and never had any
+   messages in it, then lack of the list of UIDs is interpreted as an
+   empty set of UIDs.
+
+   Thus, the client can process just these pending events and need not
+   perform a full resynchronization.  Without the message sequence
+   number matching information, the result of this step is semantically
+   equivalent to the client issuing:
+   tag1 UID FETCH "known-uids" (FLAGS) (CHANGEDSINCE
+   "mod-sequence-value" VANISHED)
+
+   Example:
+      C: A03 SELECT INBOX (QRESYNC (67890007
+         90060115194045000 41,43:211,214:541))
+      S: * OK [CLOSED]
+      S: * 314 EXISTS
+      S: * 15 RECENT
+      S: * OK [UIDVALIDITY 67890007] UIDVALIDITY
+      S: * OK [UIDNEXT 567] Predicted next UID
+      S: * OK [HIGHESTMODSEQ 90060115205545359]
+      S: * OK [UNSEEN 7] There are some unseen messages in the mailbox
+      S: * FLAGS (\Answered \Flagged \Draft \Deleted \Seen)
+      S: * OK [PERMANENTFLAGS (\Answered \Flagged \Draft
+         \Deleted \Seen \*)] Permanent flags
+      S: * VANISHED (EARLIER) 41,43:116,118,120:211,214:540
+      S: * 49 FETCH (UID 117 FLAGS (\Seen \Answered) MODSEQ
+         (90060115194045001))
+      S: * 50 FETCH (UID 119 FLAGS (\Draft $MDNSent) MODSEQ
+         (90060115194045308))
+      S: ...
+      S: * 100 FETCH (UID 541 FLAGS (\Seen $Forwarded) MODSEQ
+         (90060115194045001))
+      S: A03 OK [READ-WRITE] mailbox selected
+
+   Message sequence match data:
+
+   A client MAY provide a parenthesized list of a message sequence set
+   and the corresponding UID sets.  Both MUST be provided in ascending
+   order.  The server uses this data to restrict the range for which it
+   provides expunged message information.
+
+
+
+Melnikov, et al.            Standards Track                     [Page 6]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   Conceptually, the client provides a small sample of sequence numbers
+   for which it knows the corresponding UIDs.  The server then compares
+   each sequence number and UID pair the client provides with the
+   current state of the mailbox.  If a pair matches, then the client
+   knows of any expunges up to, and including, the message, and thus
+   will not include that range in the VANISHED response, even if the
+   "mod-sequence-value" provided by the client is too old for the server
+   to have data of when those messages were expunged.
+
+   Thus, if the Nth message number in the first set in the list is 4,
+   and the Nth UID in the second set in the list is 8, and the mailbox's
+   fourth message has UID 8, then no UIDs equal to or less than 8 are
+   present in the VANISHED response.  If the (N+1)th message number is
+   12, and the (N+1)th UID is 24, and the (N+1)th message in the mailbox
+   has UID 25, then the lowest UID included in the VANISHED response
+   would be 9.
+
+   In the following two examples, the server is unable to remember
+   expunges at all, and only UIDs with messages divisible by three are
+   present in the mailbox.  In the first example, the client does not
+   use the fourth parameter; in the second, it provides it.  This
+   example is somewhat extreme, but shows that judicious usage of the
+   sequence match data can save a substantial amount of bandwidth.
+
+   Example:
+      C: A04 SELECT INBOX (QRESYNC (67890007
+         90060115194045000 1:29997))
+      S: * 10003 EXISTS
+      S: * 5 RECENT
+      S: * OK [UIDVALIDITY 67890007] UIDVALIDITY
+      S: * OK [UIDNEXT 30013] Predicted next UID
+      S: * OK [HIGHESTMODSEQ 90060115205545359]
+      S: * OK [UNSEEN 7] There are some unseen messages in the mailbox
+      S: * FLAGS (\Answered \Flagged \Draft \Deleted \Seen)
+      S: * OK [PERMANENTFLAGS (\Answered \Flagged \Draft
+         \Deleted \Seen \*)] Permanent flags
+      S: * VANISHED (EARLIER) 1:2,4:5,7:8,10:11,13:14 [...]
+         29998:29999,30001:30002,30004:30005,30007:30008
+      S: * 9889 FETCH (UID 29667 FLAGS (\Seen \Answered) MODSEQ
+         (90060115194045027))
+      S: * 9890 FETCH (UID 29670 FLAGS (\Draft $MDNSent) MODSEQ
+         (90060115194045028))
+      S: ...
+      S: * 9999 FETCH (UID 29997 FLAGS (\Seen $Forwarded) MODSEQ
+         (90060115194045031))
+      S: A04 OK [READ-WRITE] mailbox selected
+
+
+
+
+
+Melnikov, et al.            Standards Track                     [Page 7]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   Example:
+      C: B04 SELECT INBOX (QRESYNC (67890007
+         90060115194045000 1:29997 (5000,7500,9000,9990:9999 15000,
+         22500,27000,29970,29973,29976,29979,29982,29985,29988,29991,
+         29994,29997)))
+      S: * 10003 EXISTS
+      S: * 5 RECENT
+      S: * OK [UIDVALIDITY 67890007] UIDVALIDITY
+      S: * OK [UIDNEXT 30013] Predicted next UID
+      S: * OK [HIGHESTMODSEQ 90060115205545359]
+      S: * OK [UNSEEN 7] There are some unseen messages in the mailbox
+      S: * FLAGS (\Answered \Flagged \Draft \Deleted \Seen)
+      S: * OK [PERMANENTFLAGS (\Answered \Flagged \Draft
+         \Deleted \Seen \*)] Permanent flags
+      S: * VANISHED (EARLIER) 29998:29999,30001:30002,30004:30005,30007:
+         30008
+      S: * 9889 FETCH (UID 29667 FLAGS (\Seen \Answered) MODSEQ
+         (90060115194045027))
+      S: * 9890 FETCH (UID 29670 FLAGS (\Draft $MDNSent) MODSEQ
+         (90060115194045028))
+      S: ...
+      S: * 9999 FETCH (UID 29997 FLAGS (\Seen $Forwarded) MODSEQ
+         (90060115194045031))
+      S: B04 OK [READ-WRITE] mailbox selected
+
+3.2.  VANISHED UID FETCH Modifier
+
+   [IMAPABNF] has extended the syntax of the FETCH and UID FETCH
+   commands to include an optional FETCH modifier.  This document
+   defines a new UID FETCH modifier: VANISHED.
+
+   Note, that the VANISHED UID FETCH modifier is NOT allowed with a
+   FETCH command.  The server MUST return a tagged BAD response if this
+   response is specified as a modifier to the FETCH command.
+
+   A server MUST respond with a tagged BAD response if the VANISHED UID
+   FETCH modifier is specified and the client hasn't issued "ENABLE
+   QRESYNC" in the current connection.
+
+   The VANISHED UID FETCH modifier MUST only be specified together with
+   the CHANGEDSINCE UID FETCH modifier.
+
+   The VANISHED UID FETCH modifier instructs the server to report those
+   messages from the UID set parameter that have been expunged and whose
+   associated mod-sequence is larger than the specified mod-sequence.
+   That is, the client requests to be informed of messages from the
+   specified set that were expunged since the specified mod-sequence.
+   Note that the mod-sequence(s) associated with these messages were
+
+
+
+Melnikov, et al.            Standards Track                     [Page 8]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   updated when the messages were expunged (as described above).  The
+   expunged messages are reported using the VANISHED response as
+   described in Section 3.6, which MUST contain the EARLIER tag.  Any
+   VANISHED (EARLIER) responses MUST be returned before any FETCH
+   responses, as otherwise the client might get confused about how
+   message numbers map to UIDs.
+
+   Note: A server that receives a mod-sequence smaller than <minmodseq>,
+   where <minmodseq> is the value of the smallest expunged mod-sequence
+   it remembers minus one, MUST behave as if it was requested to report
+   all expunged messages from the provided UID set parameter.
+
+   Example 1: Without the VANISHED UID FETCH modifier, a CONDSTORE-aware
+   client [CONDSTORE] needs to issue separate commands to learn of flag
+   changes and expunged messages since the last synchronization:
+
+   C: s100 UID FETCH 300:500 (FLAGS) (CHANGEDSINCE 12345)
+   S: * 1 FETCH (UID 404 MODSEQ (65402) FLAGS (\Seen))
+   S: * 2 FETCH (UID 406 MODSEQ (75403) FLAGS (\Deleted))
+   S: * 4 FETCH (UID 408 MODSEQ (29738) FLAGS ($NoJunk
+       $AutoJunk $MDNSent))
+   S: s100 OK FETCH completed
+   C: s101 UID SEARCH 300:500
+   S: * SEARCH 404 406 407 408 410 412
+   S: s101 OK search completed
+
+   Where 300 and 500 are the lowest and highest UIDs from client's
+   cache.  The second SEARCH response tells the client that the messages
+   with UIDs 407, 410, and 412 are still present, but their flags
+   haven't changed since the specified modification sequence.
+
+   Using the VANISHED UID FETCH modifier, it is sufficient to issue only
+   a single command:
+
+   C: s100 UID FETCH 300:500 (FLAGS) (CHANGEDSINCE 12345
+       VANISHED)
+   S: * VANISHED (EARLIER) 300:310,405,411
+   S: * 1 FETCH (UID 404 MODSEQ (65402) FLAGS (\Seen))
+   S: * 2 FETCH (UID 406 MODSEQ (75403) FLAGS (\Deleted))
+   S: * 4 FETCH (UID 408 MODSEQ (29738) FLAGS ($NoJunk
+       $AutoJunk $MDNSent))
+   S: s100 OK FETCH completed
+
+
+
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                     [Page 9]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+3.3.  EXPUNGE Command
+
+   Arguments: none
+
+   Responses: untagged responses: EXPUNGE or VANISHED
+
+   Result: OK - expunge completed
+           NO - expunge failure: can't expunge (e.g., permission denied)
+           BAD - command unknown or arguments invalid
+
+   This section updates the definition of the EXPUNGE command described
+   in Section 6.4.3 of [RFC3501].
+
+   The EXPUNGE command permanently removes all messages that have the
+   \Deleted flag set from the currently selected mailbox.  Before
+   returning an OK to the client, those messages that are removed are
+   reported using a VANISHED response or EXPUNGE responses.
+
+   If the server is capable of storing modification sequences for the
+   selected mailbox, it MUST increment the per-mailbox mod-sequence if
+   at least one message was permanently removed due to the execution of
+   the EXPUNGE command.  For each permanently removed message, the
+   server MUST remember the incremented mod-sequence and corresponding
+   UID.  If at least one message got expunged, the server MUST send the
+   updated per-mailbox modification sequence using the HIGHESTMODSEQ
+   response code (defined in [CONDSTORE]) in the tagged OK response.
+
+      Example:    C: A202 EXPUNGE
+                  S: * 3 EXPUNGE
+                  S: * 3 EXPUNGE
+                  S: * 5 EXPUNGE
+                  S: * 8 EXPUNGE
+                  S: A202 OK [HIGHESTMODSEQ 20010715194045319] expunged
+
+   Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag
+   set.  The first "* 3 EXPUNGE" reports message # 3 as expunged.  The
+   second "* 3 EXPUNGE" reports message # 4 as expunged (the message
+   number got decremented due to the previous EXPUNGE response).  See
+   the description of the EXPUNGE response in [RFC3501] for further
+   explanation.
+
+   Note that if the server chooses to always send VANISHED responses
+   instead of EXPUNGE responses, the previous example might look like
+   this:
+
+      Example:    C: B202 EXPUNGE
+                  S: * VANISHED 405,407,410,425
+                  S: B202 OK [HIGHESTMODSEQ 20010715194045319] expunged
+
+
+
+Melnikov, et al.            Standards Track                    [Page 10]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   Here messages with message numbers 3, 4, 7, and 11 have respective
+   UIDs 405, 407, 410, and 425.
+
+3.4.  CLOSE Command
+
+   Arguments: none
+
+   Responses: no specific responses for this command
+
+   Result: OK - close completed, now in authenticated state
+           BAD - command unknown or arguments invalid
+
+   This section updates the definition of the CLOSE command described in
+   Section 6.4.2 of [RFC3501].
+
+   The CLOSE command permanently removes all messages that have the
+   \Deleted flag set from the currently selected mailbox, and returns to
+   the authenticated state from the selected state.  No untagged EXPUNGE
+   (or VANISHED) responses are sent.
+
+   If the server is capable of storing modification sequences for the
+   selected mailbox, it MUST increment the per-mailbox mod-sequence if
+   at least one message was permanently removed due to the execution of
+   the CLOSE command.  For each permanently removed message, the server
+   MUST remember the incremented mod-sequence and corresponding UID.  If
+   at least one message got expunged, the server MUST send the updated
+   per-mailbox modification sequence using the HIGHESTMODSEQ response
+   code (defined in [CONDSTORE]) in the tagged OK response.
+
+      Example:    C: A202 CLOSE
+                  S: A202 OK [HIGHESTMODSEQ 20010715194045319] done
+
+3.5.  UID EXPUNGE Command
+
+   Arguments: message set
+
+   Responses: untagged responses: EXPUNGE or VANISHED
+
+   Result: OK - expunge completed
+           NO - expunge failure: can't expunge (e.g., permission denied)
+           BAD - command unknown or arguments invalid
+
+   This section updates the definition of the UID EXPUNGE command
+   described in Section 2.1 of [UIDPLUS].  Servers that implement both
+   [UIDPLUS] and QRESYNC extensions must implement UID EXPUNGE as
+   described in this section.
+
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 11]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   The UID EXPUNGE command permanently removes from the currently
+   selected mailbox all messages that both have the \Deleted flag set
+   and have a UID that is included in the specified message set.  If a
+   message either does not have the \Deleted flag set or has a UID that
+   is not included in the specified message set, it is not affected.
+
+   This command is particularly useful for disconnected mode clients.
+   By using UID EXPUNGE instead of EXPUNGE when resynchronizing with the
+   server, the client can avoid inadvertently removing any messages that
+   have been marked as \Deleted by other clients between the time that
+   the client was last connected and the time the client resynchronizes.
+
+   Before returning an OK to the client, those messages that are removed
+   are reported using a VANISHED response or EXPUNGE responses.
+
+   If the server is capable of storing modification sequences for the
+   selected mailbox, it MUST increment the per-mailbox mod-sequence if
+   at least one message was permanently removed due to the execution of
+   the UID EXPUNGE command.  For each permanently removed message, the
+   server MUST remember the incremented mod-sequence and corresponding
+   UID.  If at least one message got expunged, the server MUST send the
+   updated per-mailbox modification sequence using the HIGHESTMODSEQ
+   response code (defined in [CONDSTORE]) in the tagged OK response.
+
+   Example:    C: . UID EXPUNGE 3000:3002
+               S: * 3 EXPUNGE
+               S: * 3 EXPUNGE
+               S: * 3 EXPUNGE
+               S: . OK [HIGHESTMODSEQ 20010715194045319] Ok
+
+   Note: In this example, at least messages with message numbers 3, 4,
+   and 5 (UIDs 3000 to 3002) had the \Deleted flag set.  The first "* 3
+   EXPUNGE" reports message # 3 as expunged.  The second "* 3 EXPUNGE"
+   reports message # 4 as expunged (the message number got decremented
+   due to the previous EXPUNGE response).  See the description of the
+   EXPUNGE response in [RFC3501] for further explanation.
+
+3.6.  VANISHED Response
+
+   Contents:  an optional EARLIER tag
+
+   list of UIDs
+
+   The VANISHED response reports that the specified UIDs have been
+   permanently removed from the mailbox.  This response is similar to
+   the EXPUNGE response [RFC3501]; however, it can return information
+   about multiple messages, and it returns UIDs instead of message
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 12]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   numbers.  The first benefit saves bandwidth, while the second is more
+   convenient for clients that only use UIDs to access the IMAP server.
+
+   The VANISHED response has the same restrictions on when it can be
+   sent as does the EXPUNGE response (see below).
+
+   The VANISHED response has two forms.  The first form contains the
+   EARLIER tag, which signifies that the response was caused by a UID
+   FETCH (VANISHED) or a SELECT/EXAMINE (QRESYNC) command.  This
+   response is sent if the UID set parameter to the UID FETCH (VANISHED)
+   command includes UIDs of messages that are no longer in the mailbox.
+   When the client sees a VANISHED EARLIER response, it MUST NOT
+   decrement message sequence numbers for each successive message in the
+   mailbox.
+
+   The second form doesn't contain the EARLIER tag and is described
+   below.  Once a client has issued "ENABLE QRESYNC", the server SHOULD
+   use the VANISHED response without the EARLIER tag instead of the
+   EXPUNGE response.  The server SHOULD continue using VANISHED in lieu
+   of EXPUNGE for the duration of the connection.  In particular, this
+   affects the EXPUNGE [RFC3501] and UID EXPUNGE [UIDPLUS] commands, as
+   well as messages expunged in other connections.  Such a VANISHED
+   response MUST NOT contain the EARLIER tag.
+
+   A VANISHED response sent because of an EXPUNGE or UID EXPUNGE command
+   or because messages were expunged in other connections (i.e., the
+   VANISHED response without the EARLIER tag) also decrements the number
+   of messages in the mailbox; it is not necessary for the server to
+   send an EXISTS response with the new value.  It also decrements
+   message sequence numbers for each successive message in the mailbox
+   (see the example at the end of this section).  Note that a VANISHED
+   response caused by EXPUNGE, UID EXPUNGE, or messages expunged in
+   other connections SHOULD only contain UIDs for messages expunged
+   since the last VANISHED/EXPUNGE response sent for the currently
+   opened mailbox or since the mailbox was opened.  That is, servers
+   SHOULD NOT send UIDs for previously expunged messages, unless
+   explicitly requested to do so by the UID FETCH (VANISHED) command.
+
+   Note that client implementors must take care to properly decrement
+   the number of messages in the mailbox even if a server violates this
+   last SHOULD or repeats the same UID multiple times in the returned
+   UID set.  In general, this means that a client using this extension
+   should either avoid using message numbers entirely, or have a
+   complete mapping of UIDs to message sequence numbers for the selected
+   mailbox.
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 13]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   Because clients handle the two different forms of the VANISHED
+   response differently, servers MUST NOT report UIDs resulting from a
+   UID FETCH (VANISHED) or a SELECT/EXAMINE (QRESYNC) in the same
+   VANISHED response as UIDs of messages expunged now (i.e., messages
+   expunged in other connections).  Instead, the server MUST send
+   separate VANISHED responses: one with the EARLIER tag and one
+   without.
+
+   A VANISHED response MUST NOT be sent when no command is in progress,
+   nor while responding to a FETCH, STORE, or SEARCH command.  This rule
+   is necessary to prevent a loss of synchronization of message sequence
+   numbers between client and server.  A command is not "in progress"
+   until the complete command has been received; in particular, a
+   command is not "in progress" during the negotiation of command
+   continuation.
+
+   Note: UID FETCH, UID STORE, and UID SEARCH are different commands
+   from FETCH, STORE, and SEARCH.  A VANISHED response MAY be sent
+   during a UID command.  However, the VANISHED response MUST NOT be
+   sent during a UID SEARCH command that contains message numbers in the
+   search criteria.
+
+   The update from the VANISHED response MUST be recorded by the client.
+
+   Example: Let's assume that there is the following mapping between
+   message numbers and UIDs in the currently selected mailbox (here "X"
+   marks messages with the \Deleted flag set, and "x" represents UIDs
+   which are not relevant for the example):
+
+   Message numbers:   1    2    3    4    5  6   7  8  9 10  11
+   UIDs:              x  504  505  507  508  x 510  x  x  x 625
+   \Deleted messages:           X    X           X            X
+
+   In the presence of the extension defined in this document:
+
+   C: A202 EXPUNGE
+   S: * VANISHED 505,507,510,625
+   S: A202 OK EXPUNGE completed
+
+   Without the QRESYNC extension, the same example might look like:
+
+   C: A202 EXPUNGE
+   S: * 3 EXPUNGE
+   S: * 3 EXPUNGE
+   S: * 5 EXPUNGE
+   S: * 8 EXPUNGE
+   S: A202 OK EXPUNGE completed
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 14]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   (Continuing previous example) If subsequently messages with UIDs 504
+   and 508 got marked as \Deleted:
+
+   C: A210 EXPUNGE
+   S: * VANISHED 504,508
+   S: A210 OK EXPUNGE completed
+
+   i.e., the last VANISHED response only contains UIDs of messages
+   expunged since the previous VANISHED response.
+
+3.7.  CLOSED Response Code
+
+   The CLOSED response code has no parameters.  A server implementing
+   the extension defined in this document MUST return the CLOSED
+   response code when the currently selected mailbox is closed
+   implicitly using the SELECT/EXAMINE command on another mailbox.  The
+   CLOSED response code serves as a boundary between responses for the
+   previously opened mailbox (which was closed) and the newly selected
+   mailbox: all responses before the CLOSED response code relate to the
+   mailbox that was closed, and all subsequent responses relate to the
+   newly opened mailbox.
+
+   There is no need to return the CLOSED response code on completion of
+   the CLOSE or the UNSELECT [UNSELECT] command (or similar) whose
+   purpose is to close the currently selected mailbox without opening a
+   new one.
+
+4.  Server Implementation Considerations
+
+   This section describes a minimalist implementation, a moderate
+   implementation, and an example of a full implementation.
+
+4.1.  Server Implementations That Don't Store Extra State
+
+   Strictly speaking, a server implementation that doesn't remember mod-
+   sequences associated with expunged messages can be considered
+   compliant with this specification.  Such implementations return all
+   expunged messages specified in the UID set of the UID FETCH
+   (VANISHED) command every time, without paying attention to the
+   specified CHANGEDSINCE mod-sequence.  Such implementations are
+   discouraged, as they can end up returning VANISHED responses that are
+   bigger than the result of a UID SEARCH command for the same UID set.
+
+   Clients that use the message sequence match data can reduce the scope
+   of this VANISHED response substantially in the typical case where
+   expunges have not happened, or happen only toward the end of the
+   mailbox.
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 15]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+4.2.  Server Implementations Storing Minimal State
+
+   A server that stores the HIGHESTMODSEQ value at the time of the last
+   EXPUNGE can omit the VANISHED response when a client provides a
+   MODSEQ value that is equal to, or higher than, the current value of
+   this datum, that is, when there have been no EXPUNGEs.
+
+   A client providing message sequence match data can reduce the scope
+   as above.  In the case where there have been no expunges, the server
+   can ignore this data.
+
+4.3.  Additional State Required on the Server
+
+   When compared to the [CONDSTORE] extension, this extension requires
+   servers to store additional state associated with expunged messages.
+   Note that implementations are not required to store this state in
+   persistent storage; however, use of persistent storage is advisable.
+
+   One possible way to correctly implement the extension described in
+   this document is to store a queue of <UID set, mod-sequence> pairs.
+   <UID set> can be represented as a sequence of <min UID, max UID>
+   pairs.
+
+   When messages are expunged, one or more entries are added to the
+   queue tail.
+
+   When the server receives a request to return messages expunged since
+   a given mod-sequence, it will search the queue from the tail (i.e.,
+   going from the highest expunged mod-sequence to the lowest) until it
+   sees the first record with a mod-sequence less than or equal to the
+   given mod-sequence or it reaches the head of the queue.
+
+   Note that indefinitely storing information about expunged messages
+   can cause storage and related problems for an implementation.  In the
+   worst case, this could result in almost 64Gb of storage for each IMAP
+   mailbox.  For example, consider an implementation that stores <min
+   UID, max UID, mod-sequence> triples for each range of messages
+   expunged at the same time.  Each triple requires 16 octets: 4 octets
+   for each of the two UIDs, and 8 octets for the mod-sequence.  Assume
+   that there is a mailbox containing a single message with a UID of
+   2**32-1 (the maximum possible UID value), where messages had
+   previously existed with UIDs starting at 1, and have been expunged
+   one at a time.  For this mailbox alone, storage is required for the
+   triples <1, 1, modseq1>, <2, 2, modseq2>, ..., <2**32-2, 2**32-2,
+   modseq4294967294>.
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 16]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   Hence, implementations are encouraged to adopt strategies to protect
+   against such storage problems, such as limiting the size of the queue
+   used to store mod-sequences for expunged messages and "expiring"
+   older records when this limit is reached.  When the selected
+   implementation-specific queue limit is reached, the oldest record(s)
+   are deleted from the queue (note that such records are located at the
+   queue head).  For all such "expired" records, the server needs to
+   store a single mod-sequence, which is the highest mod-sequence for
+   all "expired" expunged messages.
+
+   Note that if the client provides the message sequence match data,
+   this can heavily reduce the data cost of sending a complete set of
+   missing UIDs; thus, reducing the problems for clients if a server is
+   unable to persist much of this queue.  If the queue contains data
+   back to the requested mod-sequence, this data can be ignored.
+
+   Also, note that if the UIDVALIDITY of the mailbox changes or if the
+   mailbox is deleted, then any state associated with expunged messages
+   doesn't need to be preserved and SHOULD be deleted.
+
+5.  Updated Synchronization Sequence
+
+   This section updates the description of optimized synchronization in
+   Section 6.1 of the [IMAP-DISC].
+
+   An advanced disconnected mail client should use the QRESYNC and
+   [CONDSTORE] extensions when they are supported by the server.  The
+   client uses the value from the HIGHESTMODSEQ OK response code
+   received on mailbox opening to determine if it needs to
+   resynchronize.  Once the synchronization is complete, it MUST cache
+   the received value (unless the mailbox UIDVALIDITY value has changed;
+   see below).  The client MUST update its copy of the HIGHESTMODSEQ
+   value whenever the server sends a subsequent HIGHESTMODSEQ OK
+   response code.
+
+   After completing a full synchronization, the client MUST also take
+   note of any unsolicited MODSEQ FETCH data items received from the
+   server.  Whenever the client receives a tagged response to a command,
+   it calculates the highest value among all MODSEQ FETCH data items
+   received since the last tagged response.  If this value is bigger
+   than the client's copy of the HIGHESTMODSEQ value, then the client
+   MUST use this value as its new HIGHESTMODSEQ value.
+
+   Note: It is not safe to update the client's copy of the HIGHESTMODSEQ
+   value with a MODSEQ FETCH data item value as soon as it is received
+   because servers are not required to send MODSEQ FETCH data items in
+   increasing modseqence order.  This can lead to the client missing
+   some changes in case of connectivity loss.
+
+
+
+Melnikov, et al.            Standards Track                    [Page 17]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   When opening the mailbox for synchronization, the client uses the
+   QRESYNC parameter to the SELECT/EXAMINE command.  The QRESYNC
+   parameter is followed by the UIDVALIDITY and mailbox HIGHESTMODSEQ
+   values, as known to the client.  It can be optionally followed by the
+   set of UIDs, for example, if the client is only interested in partial
+   synchronization of the mailbox.  The client may also transmit a list
+   containing its knowledge of message numbers.
+
+   If the SELECT/EXAMINE command is successful, the client compares
+   UIDVALIDITY as described in step d)1) in Section 3 of the
+   [IMAP-DISC].  If the cached UIDVALIDITY value matches the one
+   returned by the server and the server also returns the HIGHESTMODSEQ
+   response code, then the server reports expunged messages and returns
+   flag changes for all messages specified by the client in the UID set
+   parameter (or for all messages in the mailbox, if the client omitted
+   the UID set parameter).  At this point, the client is synchronized,
+   except for maybe the new messages.
+
+   If upon a successful SELECT/EXAMINE (QRESYNC) command the client
+   receives a NOMODSEQ OK untagged response (instead of the
+   HIGHESTMODSEQ response code), it MUST remove the last known
+   HIGHESTMODSEQ value from its cache and follow the more general
+   instructions in Section 3 of the [IMAP-DISC].
+
+   At this point, the client is in sync with the server regarding old
+   messages.  This client can now fetch information about new messages
+   (if requested by the user).
+
+   Step d) ("Server-to-client synchronization") in Section 4 of the
+   [IMAP-DISC] in the presence of the QRESYNC & CONDSTORE extensions is
+   amended as follows:
+
+   d) "Server-to-client synchronization" -- for each mailbox that
+      requires synchronization, do the following:
+
+   1a) Check the mailbox UIDVALIDITY (see Section 4.1 of the [IMAP-DISC]
+       for more details) after issuing SELECT/EXAMINE (QRESYNC) command.
+
+       If the UIDVALIDITY value returned by the server differs, the
+       client MUST
+
+       *   empty the local cache of that mailbox;
+
+       *   "forget" the cached HIGHESTMODSEQ value for the mailbox;
+
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 18]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+       *   remove any pending "actions" which refer to UIDs in that
+           mailbox.  Note, this doesn't affect actions performed on
+           client generated fake UIDs (see Section 5 of the
+           [IMAP-DISC]);
+
+   2)  Fetch the current "descriptors";
+
+       I) Discover new messages.
+
+   3)  Fetch the bodies of any "interesting" messages that the client
+       doesn't already have.
+
+   Example: The UIDVALIDITY value is the same, but the HIGHESTMODSEQ
+            value has changed on the server while the client was
+            offline:
+
+    C: A142 SELECT INBOX (QRESYNC (3857529045 20010715194032001 1:198))
+    S: * 172 EXISTS
+    S: * 1 RECENT
+    S: * OK [UNSEEN 12] Message 12 is first unseen
+    S: * OK [UIDVALIDITY 3857529045] UIDs valid
+    S: * OK [UIDNEXT 201] Predicted next UID
+    S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft)
+    S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited
+    S: * OK [HIGHESTMODSEQ 20010715194045007]
+    S: * VANISHED (EARLIER) 1:5,7:8,10:15
+    S: * 2 FETCH (UID 6 MODSEQ (20010715205008000)
+        FLAGS (\Deleted))
+    S: * 5 FETCH (UID 9 MODSEQ (20010715195517000)
+        FLAGS ($NoJunk $AutoJunk $MDNSent))
+       ...
+    S: A142 OK [READ-WRITE] SELECT completed
+
+6.  Formal Syntax
+
+   The following syntax specification uses the Augmented Backus-Naur
+   Form (ABNF) notation as specified in [ABNF].
+
+   Non-terminals referenced but not defined below are as defined by
+   [RFC3501], [CONDSTORE], or [IMAPABNF].
+
+   Except as noted otherwise, all alphabetic characters are case-
+   insensitive.  The use of upper or lower case characters to define
+   token strings is for editorial clarity only.  Implementations MUST
+   accept these strings in a case-insensitive fashion.
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 19]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+   capability          =/ "QRESYNC"
+
+   select-param        =  "QRESYNC" SP "(" uidvalidity SP
+                       mod-sequence-value [SP known-uids]
+                       [SP seq-match-data] ")"
+                       ;; conforms to the generic select-param
+                       ;; syntax defined in [IMAPABNF]
+
+   seq-match-data      =  "(" known-sequence-set SP known-uid-set ")"
+
+   uidvalidity         =  nz-number
+
+   known-uids          =  sequence-set
+                       ;; sequence of UIDs, "*" is not allowed
+
+   known-sequence-set  =  sequence-set
+                       ;; set of message numbers corresponding to
+                       ;; the UIDs in known-uid-set, in ascending order.
+                       ;; * is not allowed.
+
+   known-uid-set       =  sequence-set
+                       ;; set of UIDs corresponding to the messages in
+                       ;; known-sequence-set, in ascending order.
+                       ;; * is not allowed.
+
+   message-data        =/ expunged-resp
+
+   expunged-resp       =  "VANISHED" [SP "(EARLIER)"] SP known-uids
+
+   rexpunges-fetch-mod =  "VANISHED"
+                       ;; VANISHED UID FETCH modifier conforms
+                       ;; to the fetch-modifier syntax
+                       ;; defined in [IMAPABNF].  It is only
+                       ;; allowed in the UID FETCH command.
+
+   resp-text-code      =/ "CLOSED"
+
+7.  Security Considerations
+
+   As always, it is important to thoroughly test clients and servers
+   implementing this extension, as it changes how the server reports
+   expunged messages to the client.
+
+   Security considerations relevant to [CONDSTORE] are relevant to this
+   extension.
+
+   This document doesn't raise any new security concerns not already
+   raised by [CONDSTORE] or [RFC3501].
+
+
+
+Melnikov, et al.            Standards Track                    [Page 20]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+8.  IANA Considerations
+
+   IMAP4 capabilities are registered by publishing a standards track or
+   IESG approved experimental RFC.  The registry is currently located
+   at:
+
+      http://www.iana.org/assignments/imap4-capabilities
+
+   This document defines the QRESYNC IMAP capability.  IANA has added
+   this capability to the registry.
+
+9.  Acknowledgments
+
+   Thanks to Steve Hole, Cyrus Daboo, and Michael Wener for encouraging
+   creation of this document.
+
+   Valuable comments, both in agreement and in dissent, were received
+   from Timo Sirainen, Michael Wener, Randall Gellens, Arnt Gulbrandsen,
+   Chris Newman, Peter Coates, Mark Crispin, Elwyn Davies, Dan Karp,
+   Eric Rescorla, and Mike Zraly.
+
+   This document takes substantial text from [RFC3501] by Mark Crispin.
+
+10.  References
+
+10.1.  Normative References
+
+   [ABNF]       Crocker, D. and P. Overell, "Augmented BNF for Syntax
+                Specifications: ABNF", STD 68, RFC 5234, January 2008.
+
+   [CONDSTORE]  Melnikov, A. and S. Hole, "IMAP Extension for
+                Conditional STORE Operation or Quick Flag Changes
+                Resynchronization", RFC 4551, June 2006.
+
+   [ENABLE]     Gulbrandsen, A., Ed. and A. Melnikov, Ed., "The IMAP
+                ENABLE Extension", RFC 5161, March 2008.
+
+   [IMAPABNF]   Melnikov, A. and C. Daboo, "Collected Extensions to
+                IMAP4 ABNF", RFC 4466, April 2006.
+
+   [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
+                Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+   [RFC3501]    Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
+                4rev1", RFC 3501, March 2003.
+
+   [UIDPLUS]    Crispin, M., "Internet Message Access Protocol (IMAP) -
+                UIDPLUS extension", RFC 4315, December 2005.
+
+
+
+Melnikov, et al.            Standards Track                    [Page 21]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+10.2.  Informative References
+
+   [IMAP-DISC]  Melnikov, A., Ed., "Synchronization Operations For
+                Disconnected Imap4 Clients", RFC 4549, June 2006.
+
+   [UNSELECT]   Melnikov, A., "Internet Message Access Protocol (IMAP)
+                UNSELECT command", RFC 3691, February 2004.
+
+Authors' Addresses
+
+   Alexey Melnikov
+   Isode Ltd
+   5 Castle Business Village
+   36 Station Road
+   Hampton, Middlesex  TW12 2BX
+   UK
+
+   EMail: Alexey.Melnikov@isode.com
+
+
+   Dave Cridland
+   Isode Ltd
+   5 Castle Business Village
+   36 Station Road
+   Hampton, Middlesex  TW12 2BX
+   UK
+
+   EMail: dave.cridland@isode.com
+
+
+   Corby Wilson
+   Nokia
+   5 Wayside Rd.
+   Burlington, MA  01803
+   USA
+
+   EMail: corby@computer.org
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Melnikov, et al.            Standards Track                    [Page 22]
+
+RFC 5162               IMAP Quick Mailbox Resync              March 2008
+
+
+Full Copyright Statement
+
+   Copyright (C) The IETF Trust (2008).
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+Melnikov, et al.            Standards Track                    [Page 23]
+