LMTP Timeout

[Jorey Bump]

Phil Chambers wrote:
> This is an update on progress with diagnosing my problem with LMTP/IMAP hanging.
> 
> My diagnosis with reconstruct was a red herring!  While I was patching 
> reconstruct to give diagnostics Exim tried a delivery and lmtpd locked the 
> user's cyrus.header file before hanging. When I killed the lmptd proces I found 
> no problem with reconstruct.
> 
> So, back to square one.  I can't think of a way to debug this. It is imapd and 
> lmtpd which are hanging and I cannot possibly put diagnostic code into those 
> because the logs would explode on a live system.
> 
> I really need some suggestions!

Do you experience total failure after a delivery, or is this isolated to 
  a specific user agent? What happens if the connection is allowed to 
timeout? Can the user make another IMAP connection successfully?

The reason I ask is because I was experiencing similar problems with 
Thunderbird that I could not reproduce with any other MUA. In fact, I 
could not intentionally reproduce the problem with Thunderbird, either. 
While tailing the logs, I noticed that the hangups were always preceded 
by an LMTP delivery to the user experiencing the hangup, which always 
resulted in a "Connection to server mail.example.com timed out" error. I 
did not have enough evidence to conclude that this was more than a 
coincidence, however, as deliveries are relatively constant.

In order to overcome the problem, I played with various Thunderbird 
settings until something worked. I've experienced no more hangups since 
I unchecked "Use IDLE command if the server supports it". This is not 
the only setting I changed, but it is the only one that had an effect. 
Perhaps this information will prove helpful to you, anecdotal as it is.