[Dovecot] IMAP STARTTLS Problem

[Markus Fritz]

Hello,

I have this problem:
May  5 21:02:35 opsys dovecot: imap-login: Disconnected (no auth 
attempts): rip=84.150.52.31, lip=78.46.216.126

Connecting via Thunderbird to STARTTLS won't work, but with a website 
from the same server it works for tls://opsys.de.
So why is the port closed for external ip's?
IPTABLES entry for imap is this:
fail2ban-dovecot-pop3imap  tcp  --  anywhere             anywhere       
     multiport dports pop3,pop3s,imap2,imaps

Key files are correct TLS is working from localhost.

System is Debian squeeze

-- 
Markus Fritz
Administration

opsys.de