TLS not working

Question

IMAP communication between a mail server and our Unity Connection 7.x server has stopped working.  The end user stated:
"The problem we observed from our server, and which is reproducible with the openssl tool, is that the Unity Connection server doesn't respond to a login request performed over STARTTLS. Doing a simple IMAP STARTTLS test results in a hung login attempt and eventual timeout:
client: # openssl s_client -connect unityservername.domain.com:143 -starttls imap
server: <valid response>
client: 0 LOGIN username password
<no response, timeout"
On the Unity Connection server I turned on micro traces for IMAP.  In one of the resultant log files, I see this:
"09/30/2010 08:27:48.687 |3490,ClientSocket-42 10.0.24.181:-28448,,CuImapSvr,11,SSL_accept:error in SSLv3 read client certificate A: [0xFFFFFFFF; --Unknown HRESULT--]|"
The timestamp on this message corresponded with a failed test attempt.  I've tried restarting the IMAP server service.  No changes were made on the Unity Connection side between the time that this was working and the time is stopped working.
Any ideas?
Thanks.

Answer 1

Here's what the tech on the client-side observed:
"The problem we observed from Zimbra ZCS, and which is reproducible with the openssl tool, is that the Unity server does not respond to a login request performed over STARTTLS. Doing a simple IMAP STARTTLS test results in a hung login attempt and eventual timeout:
client: # openssl s_client -connect unityservername.domain.com:143 -starttls imap
server:
client: 0 LOGIN username password
So the way I interpret this (and I could be totally wrong) is that the client makes a IMAP connection over port 143 and either requests TLS or tries TLS if it is offered.  At that point, the login fails. 
The user tried a test and responded with this:
"Just did one a couple minutes ago- did SSL on 993 first w/success, then did the unencrypted one on 143 which threw the 'Generic Test Failure'"