Clients sporadically dropping connections in Murder environment

[David Mayo]

In August we introduced a Cyrus 2.2 IMAP proxy server in front of our 
Cyrus 2.2 backend server. This is the first part of the process to move 
our users' mailboxes to a Cyrus 2.3 backend server.

Since the upgrade we have had sporadic reports of users' clients 
disconnecting from the IMAP server.

One user (a fellow sysadmin) using Mulberry 4 reports that occasionally 
when they send an email, they get a message, "The draft has been sent 
successfully, but an error has occurred whilst doing post-processing." 
The message is not saved to their IMAP sent-mail folder, as configured 
in Mulberry.

We enabled telemetry logging on the user's account. There was no attempt 
to APPEND to the folder, and there were no BAD or NO responses during 
their session. No errors in Cyrus logs (although we're only logging upto 
'info' levels on the production service). The proxyd daemon hasn't 
crashed[1]. Their client checks for new messages every 2 minutes so 
presumably this keeps the connection open. People using the same client 
haven't noticed this problem.

Pine, Alpine and Evolution users have apparently also reported similar 
symptoms although I don't have any first-hand reports. No reports of 
problems from Outlook, Thunderbird or our Horde Webmail client which are 
our main supported clients.

I've looked through the list archives and can't see this being 
discussed. Has anyone else using a Murder environment seen issues like this?

We're running Solaris 10. Our front-end server is 2.2.13. Our back-end 
server is 2.2.12. The servers use GSSAPI to authenticate to each other 
and we refresh the KerberosV tickets every hour from a key tab. We 
aren't running IMAPS on the back-end server.

Any thoughts on this gratefully received!

Regards,


Dave.

David Mayo
Networks/Systems Administrator
University of Bath Computing Services, UK

[1]
proxyd has crashed a couple of times a week on the proxy server but 
that's a different matter! We will properly investigate it if the 
problems are still present when we upgrade the proxy server to Cyrus 2.3