[Zope] Secure Mailhost timing out

[lists at unep.net]

all of a sudden my Secure mailhost rfuses to connect to my postfix:
Unable to send mail: The read operation timed out

traceback:

  Module Products.SecureMailHost.SecureMailHost, line 173, in send
  Module Products.MailHost.MailHost, line 144, in send
  Module Products.SecureMailHost.SecureMailHost, line 282, in _send
  Module Products.SecureMailHost.mail, line 106, in send
  Module smtplib, line 390, in ehlo
  Module smtplib, line 344, in getreply
  Module smtplib, line 159, in readline
sslerror: The read operation timed out


and in the postfix log:

Apr 10 17:49:45 www.example.net <info> postfix/smtpd[13667]: connect from
localhost.localdomain[127.0.0.1]
Apr 10 17:49:55 www.example.net <info> postfix/smtpd[13667]: lost
connection after EHLO from localhost.localdomain[127.0.0.1]
Apr 10 17:49:55 www.example.net <info> postfix/smtpd[13667]: disconnect
from localhost.localdomain[127.0.0.1]

this only happens in my plone 2.1.2 Instance, the 2.0.5 and 2.1.1
Instances have no problem at all (on the same machine, using the same
smtpd) so this is not firewall related.

The only change in the configuration was that I installed ZMySQL DA

any pointers?

christian