Changes have been made in Git (develop):

commit c37f6c6832d708743ccb1e41b4e432cf0ec5ff03
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Thu Oct 4 15:41:47 2012 -0600

     Bug #11453: Fix grabbing the remaining string in a tokenizer stream

  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |   38 
++++++++++----------
  .../Imap_Client/lib/Horde/Imap/Client/Tokenize.php |    2 +-
  .../test/Horde/Imap/Client/SocketTest.php          |    7 +++-
  3 files changed, 26 insertions(+), 21 deletions(-)

http://git.horde.org/horde-git/-/commit/c37f6c6832d708743ccb1e41b4e432cf0ec5ff03

Changes have been made in Git (develop):

commit db07b040d60942cb57a186802d5c69f924b084cd
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Thu Oct 4 13:28:59 2012 -0600

     Bug #11453: Fix parsing bare response text codes

  .../lib/Horde/Imap/Client/Interaction/Server.php   |    6 +++++-
  .../test/Horde/Imap/Client/SocketTest.php          |   15 +++++++++++++++
  .../test/Horde/Imap/Client/Stub/Socket.php         |    8 ++++++++
  3 files changed, 28 insertions(+), 1 deletions(-)

http://git.horde.org/horde-git/-/commit/db07b040d60942cb57a186802d5c69f924b084cd

Changes have been made in Git (develop):

commit 9fd6433e813fe55b8601a35b418cd5ac815fc17f
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Wed Oct 3 11:47:41 2012 -0600

     [mms] Store command that caused NO/BAD error in Exception, if it 
can be determined.

     Also, ignore untagged NO responses - these are warnings, not fatal, and
     generally will include response text codes that will be parsed elsewhere
     in the code.  Should fix Bug #11453

  .../Horde/Imap/Client/Exception/ServerResponse.php |   14 +++++++-
  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |   37 +++++++++++++++++--
  framework/Imap_Client/package.xml                  |    2 +
  3 files changed, 48 insertions(+), 5 deletions(-)

http://git.horde.org/horde-git/-/commit/9fd6433e813fe55b8601a35b418cd5ac815fc17f

Changes have been made in Git (develop):

commit 472a1e509d02de485104667e1637f57f14eb3993
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Mon Oct 1 15:39:40 2012 -0600

     Bug #11453: Correct fix for parsing a FETCH VANISHED response

  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |    2 +-
  1 files changed, 1 insertions(+), 1 deletions(-)

http://git.horde.org/horde-git/-/commit/472a1e509d02de485104667e1637f57f14eb3993

Changes have been made in Git (develop):

commit 6e2c84eca7368cc7a138a59a71f2733b3fc289f1
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Mon Oct 1 15:38:47 2012 -0600

     Bug #11453: Fix parsing a FETCH VANISHED response

  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |    8 ++++----
  1 files changed, 4 insertions(+), 4 deletions(-)

http://git.horde.org/horde-git/-/commit/6e2c84eca7368cc7a138a59a71f2733b3fc289f1

The original issues all seem to have been fixed now.

Changes have been made in Git (master):

commit c37f6c6832d708743ccb1e41b4e432cf0ec5ff03
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Thu Oct 4 15:41:47 2012 -0600

     Bug #11453: Fix grabbing the remaining string in a tokenizer stream

  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |   38 
++++++++++----------
  .../Imap_Client/lib/Horde/Imap/Client/Tokenize.php |    2 +-
  .../test/Horde/Imap/Client/SocketTest.php          |    7 +++-
  3 files changed, 26 insertions(+), 21 deletions(-)

http://git.horde.org/horde-git/-/commit/c37f6c6832d708743ccb1e41b4e432cf0ec5ff03

Almost there, only the mailbox is missing. The notification text now 
is "is at xy% quota".

This has been fixed.

Changes have been made in Git (master):

commit db07b040d60942cb57a186802d5c69f924b084cd
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Thu Oct 4 13:28:59 2012 -0600

     Bug #11453: Fix parsing bare response text codes

  .../lib/Horde/Imap/Client/Interaction/Server.php   |    6 +++++-
  .../test/Horde/Imap/Client/SocketTest.php          |   15 +++++++++++++++
  .../test/Horde/Imap/Client/Stub/Socket.php         |    8 ++++++++
  3 files changed, 28 insertions(+), 1 deletions(-)

http://git.horde.org/horde-git/-/commit/db07b040d60942cb57a186802d5c69f924b084cd

In fact, this sounds exactly what I previously suggested in Ticket #11427.

This has nothing to do with the IMAP client though.  Please open 
another ticket.

Same here

I can reliably reproduce this now, just hitting Down and Delete 
quickly after navigating to a mailbox.

I still see the "Cannot open message" errors. I see those mostly when 
deleting messages. Could this be happening: I navigate to a message 
and hit Delete. The showMessage request is sent, the session is 
temporarily closed, the deleteMessages request is sent and executed 
immediately because the session is not locked. The delete request is 
completed faster than the showMessage request, so that some action on 
the message fails, like flagging as seen.

The errors are gone, but I still don't get warning notifications from 
untagged responses.

No.  Instead the issue was that we were throwing exceptions on 
untagged NO responses, where this indicates a warning, not a fatal 
error.  This commit should fix that.

Changes have been made in Git (master):

commit 9fd6433e813fe55b8601a35b418cd5ac815fc17f
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Wed Oct 3 11:47:41 2012 -0600

     [mms] Store command that caused NO/BAD error in Exception, if it 
can be determined.

     Also, ignore untagged NO responses - these are warnings, not fatal, and
     generally will include response text codes that will be parsed elsewhere
     in the code.  Should fix Bug #11453

  .../Horde/Imap/Client/Exception/ServerResponse.php |   14 +++++++-
  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |   37 +++++++++++++++++--
  framework/Imap_Client/package.xml                  |    2 +
  3 files changed, 48 insertions(+), 5 deletions(-)

http://git.horde.org/horde-git/-/commit/9fd6433e813fe55b8601a35b418cd5ac815fc17f

Could this be a parsing error with IMAP ALERTs?

I'm currently always around the quota limit, and I just noticed that I 
didn't get quota warnings for a while. This would also explain why 
these errors come and go, because 1) sometimes I'm over, sometimes 
under the limit, and 2) the server doesn't respond each request with 
an ALERT. Example:
S: * OK [CAPABILITY IMAP4rev1 LITERAL+ ID ENABLE  XIMAPPROXY] neo 
Cyrus IMAP v2.4.12-Debian-2.4.12-2 server ready
C: [LOGIN Command - username: jan]
S: * OK [XPROXYREUSE] IMAP connection reused by imapproxy
S: 1 OK User logged in
C: 2 ENABLE QRESYNC
S: * ENABLED
S: 2 OK Completed
C: 3 SELECT "INBOX.Quarant&AOQ-ne" (CONDSTORE)
S: * 24 EXISTS
S: * 0 RECENT
S: * FLAGS (\Answered \Flagged \Draft \Deleted \Seen $forwarded $junk 
$notjunk)
S: * OK [PERMANENTFLAGS (\Answered \Flagged \Draft \Deleted \Seen 
$forwarded $junk $notjunk \*)] Ok
S: * OK [UNSEEN 1] Ok
S: * OK [UIDVALIDITY 1240054819] Ok
S: * OK [UIDNEXT 56964] Ok
S: * OK [HIGHESTMODSEQ 7905] Ok
S: * OK [URLMECH INTERNAL] Ok
S: * NO [ALERT] Mailbox is at 91% of quota
C: 4 EXAMINE "INBOX.Quarant&AOQ-ne" (CONDSTORE)
S: 3 OK [READ-WRITE] Completed
C: 5 UID THREAD REFERENCES US-ASCII ALL
S: * OK [CLOSED] Ok
S: * 24 EXISTS
S: * 0 RECENT
S: * FLAGS (\Answered \Flagged \Draft \Deleted \Seen $forwarded $junk 
$notjunk)
S: * OK [PERMANENTFLAGS ()] Ok
S: * OK [UNSEEN 1] Ok
S: * OK [UIDVALIDITY 1240054819] Ok
S: * OK [UIDNEXT 56964] Ok
S: * OK [HIGHESTMODSEQ 7905] Ok
S: * OK [URLMECH INTERNAL] Ok
S: 4 OK [READ-ONLY] Completed
C: 6 STATUS "INBOX" (recent)
S: * THREAD 
(56941)((56940)(56942)(56950)(56953)(56954)(56958))((56943)(56944)(56947))((56945)(56946))(56948)(56949)(56951)(56952)(56955)((56956)(56963))(56957)((56959)(56961))(56960)(56962)
S: 5 OK Completed (24 msgs in 0.000 secs)
C: 7 STATUS "INBOX.horde.apps" (recent)
S: * STATUS INBOX (RECENT 0)
S: 6 OK Completed
C: 8 STATUS "INBOX.horde.bugs" (recent)
S: * STATUS INBOX.horde.apps (RECENT 0)
S: 7 OK Completed
C: 9 STATUS "INBOX.horde.cvs" (recent)
S: * STATUS INBOX.horde.bugs (RECENT 0)
S: 8 OK Completed
C: 10 STATUS "INBOX.horde.dev" (recent)
S: * STATUS INBOX.horde.cvs (RECENT 0)
S: 9 OK Completed
C: 11 STATUS "INBOX.horde.imp" (recent)
S: * STATUS INBOX.horde.dev (RECENT 0)
S: 10 OK Completed
C: 12 STATUS "INBOX.Privat" (recent)
S: * STATUS INBOX.horde.imp (RECENT 0)
S: 11 OK Completed
C: 13 LOGOUT
S: * STATUS INBOX.Privat (RECENT 0)
S: * BYE LOGOUT received
S: 13 OK Completed

After pulling today, my issue has been resolved.

There was an issue parsing the response EARLIER data, but that would 
not have affected you since you were getting no VANISHED response.   
This issue has been fixed.

Changes have been made in Git (master):

commit 472a1e509d02de485104667e1637f57f14eb3993
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Mon Oct 1 15:39:40 2012 -0600

     Bug #11453: Correct fix for parsing a FETCH VANISHED response

  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |    2 +-
  1 files changed, 1 insertions(+), 1 deletions(-)

http://git.horde.org/horde-git/-/commit/472a1e509d02de485104667e1637f57f14eb3993

Changes have been made in Git (master):

commit 6e2c84eca7368cc7a138a59a71f2733b3fc289f1
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Mon Oct 1 15:38:47 2012 -0600

     Bug #11453: Fix parsing a FETCH VANISHED response

  .../Imap_Client/lib/Horde/Imap/Client/Socket.php   |    8 ++++----
  1 files changed, 4 insertions(+), 4 deletions(-)

http://git.horde.org/horde-git/-/commit/6e2c84eca7368cc7a138a59a71f2733b3fc289f1

[snip]
[snip]
That code is running perfect.  There is no VANISHED response, so no 
messages have been deleted between those MODSEQs according to the 
server.

I can verify this works fine on my server.  E.g.:

C: 4 UID FETCH 1:* UID (VANISHED CHANGEDSINCE 34240)
S: * VANISHED (EARLIER) 14199,14239,14242
S: * 37 FETCH (UID 14211 MODSEQ (34251))
S: * 38 FETCH (UID 14212 MODSEQ (34250))
S: * 39 FETCH (UID 14243 MODSEQ (34249))
S: 4 OK Fetch complete

Shot in the dark: try this change in _vanished():

         $cmd = $this->_clientCommand(array(
             'UID',
             'FETCH',
             $ids->all ? '1:*' : strval($ids),
-           'UID',
+           new Horde_Imap_Client_Data_Format_List('UID'),
             new Horde_Imap_Client_Data_Format_List(array(
                 'VANISHED',
                 'CHANGEDSINCE',
                 new Horde_Imap_Client_Data_Format_Number($modseq)
             ))
         ));

Sample Code:

$imap = $registry->mail->imapOb();
$mbox = new Horde_Imap_Client_Mailbox('INBOX');
$status_flags = Horde_Imap_Client::STATUS_HIGHESTMODSEQ |
                 Horde_Imap_Client::STATUS_UIDVALIDITY |
                 Horde_Imap_Client::STATUS_UIDNEXT;

$status = $imap->status($mbox, $status_flags);
var_dump($status);

// At this point, modseq is reported as 573852
// I delete some email(s) from the INBOX, verify they are deleted by 
accessing the same INBOX on another client then:

$vanished = $imap->vanished($mbox, 573852);
var_dump($vanished->ids);

returns an empty array.


The following IMAP log is generated during the vanished call:

S: * OK [CAPABILITY IMAP4rev1 LITERAL+ LOGIN-REFERRALS ID ENABLE   
XIMAPPROXY] Dovecot ready.
C: [LOGIN Command - username: mike]
S: * OK [XPROXYREUSE] IMAP connection reused by imapproxy
S: 1 OK User logged in
C: 2 STATUS "INBOX" (uidnext uidvalidity highestmodseq)
S: * STATUS "INBOX" (UIDNEXT 138723 UIDVALIDITY 1292457115 
HIGHESTMODSEQ 573857)
S: 2 OK Status completed.
C: 3 EXAMINE "INBOX" (QRESYNC (1292457115 573857 
112036,119945:119946,123483,126397,127831,128044,130389,130457,132128,135833,136202,136302,136317,137188,137688,137690,137817,138171,138188,138214,138233,138238:138239,138254,138266:138267,138271:138273,138282,138309,138311,138314,138479:138673,138675:138708,138713:138717,138721:138722))
S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft $Junk $NotJunk 
$Forwarded Test_Tso test_one JunkRecorded $mdnsent)
S: * OK [PERMANENTFLAGS ()] Read-only mailbox.
S: * 38 EXISTS
S: * 0 RECENT
S: * OK [UNSEEN 38] First unseen.
S: * OK [UIDVALIDITY 1292457115] UIDs valid
S: * OK [UIDNEXT 138723] Predicted next UID
S: * OK [HIGHESTMODSEQ 573857] Highest
S: 3 OK [READ-ONLY] Select completed.
C: 4 UID FETCH 1:* UID (VANISHED CHANGEDSINCE 573852)
S: * 37 FETCH (UID 138721 MODSEQ (573857))
S: 4 OK Fetch completed.
C: 5 LOGOUT
S: * BYE LOGOUT received
S: 5 OK Completed

Has anything changed in the way vanished messages are reported? Since 
the recent refactoring ActiveSync is no longer picking up on expunged 
messages.

I ran the new code for about a day on my local machine, with both the 
horde/error log and IMAP debugging in the background, and I was not 
seeing any issues. Used the smartmobile view for about 10 minutes 
earlier and didn't have any issues either.  So IMAP logs of the issues 
will be necessary.

FYI: these IMAP changes have been verified to fix the DoS issue that 
was the initial reason why all of this was rewritten.

Since the refactoring, I have all kinds of random, intermittent errors 
like "Cannot open mailbox foo", "Folder structure changed on the 
server", "Cannot open message" etc. Sometimes IMP recovers with the 
next request, sometimes one has to reload IMP completely.