Subject: [Imap-uw] IMAP crash on append to sent-mail

From: Rob Henderson <[email-masked]>
Date: Mon, 20 Feb 2006 09:34:08 -0500

I have a user who is having trouble when saving copies of sent email to
their sent-mail folder via IMAP using thunderbird.  Oddly, this works for
some email but fails for others and seems to be dependent on the content
of the email being sent.  In particular, it seems to fail when sending
html content that includes certain <table> structures and the problem is
quite repeatable.  Very odd.

It seems possible that the problem is related to this thunderbird bug:

   https://bugzilla.mozilla.org/show_bug.cgi?id=206408

However, when it fails, I see the following error from imapd in the logs:

   imapd[24422]: [ID 839431 mail.alert] IMAP toolkit slave process crash: Unknown master response for append: <FF>

I was hoping that someone might be able to interpret this error message
or have other information about this problem.

Here are the details of our config:

Mail client:  Thunderbird 1.5 under Windows XP
IMAP server:  UW imapd 2004.357 under Solaris 8

Any help tracking this down would be much appreciated.

Thanks!

	--Rob
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---

From: Mark Crispin <[email-masked]>
Date: Mon, 20 Feb 2006 10:41:31 -0800

> IMAP server:  UW imapd 2004.357 under Solaris 8

This error message only occurs on SVR4 systems such as Solaris, HP-UX, 
AIX, etc.  The underlying cause is what the BSD man pages call "the 
completely stupid semantics" of POSIX file locking (fcntl() system call). 
Systems which have the flock() system call, such as BSD (including Mac OS 
X) and Linux, do not have this problem.

The outcome of these "completely stupid semantics" (harsh words, but ones 
which I agree) is that operations which deal with a named mailbox must run 
in an independent subprocess.  Otherwise, if the client does any such 
operation (DELETE, RENAME, STATUS, SCAN, COPY, APPEND) with the currently 
seleted mailbox as the target, the lock on the selected mailbox is lost. 
The most common offenders are COPY and especially APPEND (e.g., copying a 
message to the currently open mailbox).

There is a communication protocol between the master imapd and the 
subprocess.  This error message is an error in the communication protocol. 
The fact that the error was a spurious 0xff character suggests that what 
really happened is that what was passed as an EOF instead of a 0xff 
character.  That is, the master process died (perhaps because the client 
dropped the connection), and the slave found out by getting an EOF on the 
pipe.

So, although the error message is flawed (I will fix it to test for EOF), 
the underlying problem in your case is probably that the client dropped 
the connection unexpectedly.  So it's probably a Thunderbird issue, not an 
imapd issue.

Another good thing that you can do is to dump your Solaris systems in 
favor of Linux or BSD.  SVR4 is a very poor platform for IMAP servers, and 
SUN is a particularly troublesome vendor.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.
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