We have had similar SMTP probs with clients looping at TLS auth. Has anyone seen a solution? We have bodged to continue playing by selecting tls 'if available' in Thunderbird and not requiring it at the server end, most times this works. Didnt have this problem on beta 1, there was a missing -r in a conf file but its certainly there now!
We will need to clear fedora and start again I think as the prodding has caused some fun and games with other services now - logger failing and most recently MTA not starting. uninstall and reinstall of Zimbra is not curing it.
Thanks
Kevin