[Dovecot] Timed Out or Disconnect Errors on emails with attachments

[Mark Nienberg]

Tudor Holton wrote:
> Hello all,
> 
> I've migrated our Maildir system from Courier-IMAP-SSL to Dovecot with 
> SSL and now we're getting "Connection to <server> Timed Out" errors when 
> sending mail with attachments.  The mail gets sent, however it doesn't 
> save the mail in the user's "Sent" folder.
> Our IMAP and SMTP servers are different.  So the client sends to the 
> SMTP server first, completes that, and then opens a channel to Dovecot 
> and dovecot appears to receive the data (TB gives a progress bar as it's 
> sending to dovecot) and then disconnects _after_.
> 
> We have a mixed bag of clients here from Thunderbird on Linux and 
> Windows, through Outlook Express to Outlook.  All show similar errors.
> 
> I enabled the logs on dovecot, however it wasn't very informative.  At 
> the time it occurred the only line in the log file was:
> dovecot: 2007-03-13 16:21:12 Info: IMAP(tudor): Disconnected
> 
> This is obviously different from "Disconnected: Logged out".
> 
> Emails without attachments behave ok, it only occurs with emails with 
> attachments.
> 
> Has anyone else had any experience of this?

With dovecot rc15 I frequently get a time out while Thunderbird copies to the IMAP 
sent folder.  It only happens from outside my network.  The client is using SSL.  I 
never see the problem for clients on the LAN. One client on the LAN uses SSL and the 
rest (about 20) do not, so the problem may just be network latency or something not 
related to SSL.  I don't see any relationship to attachments, it happens even without.

Mark Nienberg