[Dovecot] Random Loss of Connection with Thunderbird and Dovecot

[Timo Sirainen]

On Wed, 2011-11-23 at 16:54 -0800, Jay Welch wrote:
> Dovecot Version: 1.2.16
> 
> 
> I am having issues with Thunderbird connecting to Dovecot at random 
> times. Usually an error comes up and states that Thunderbird cannot 
> connect to the server. The only way I have been able to fix this is 
> reset/repair the network connection or reboot the computer. Is there any 
> parameters I can change in Dovecot to fix this issue? Does anyone know 
> what is likely going on? I have been reading forums and I cannot find 
> anything.

Dovecot always logs the reason for logout, e.g.:

> Nov 24 02:53:24 imap(tss): Info: Connection closed in=0 out=291

This means that the connection got disconnected (i.e. Dovecot didn't do
the disconnection)

> Nov 24 02:52:47 imap(tss): Info: Disconnected: Logged out in=8 out=334

And this means that the client used a LOGOUT command.

and so on. Find the log entries about the times when you're having
problems. Dovecot logs about every single connection it sees. If you
don't see a log message about some connection, it means that Dovecot
never saw it, and the problem is outside Dovecot.

I'd first look into any antivirus/software firewalls you've installed.
They're usually the reason for connection problems with Windows.