[Mimedefang] MD and Postfix: can't read SMFIC_OPTNEG reply packet header

[Stefan König]

Hi list,

I have a set-up a new machine with MD 2.68, SA 3.3.1 and Postfix 2.6.1.
>From time to time I get an error in the mail logs like this on a
connecting client:

postfix/smtpd[22871]: warning: milter
unix:/var/spool/MIMEDefang/mimedefang.sock: can't read SMFIC_OPTNEG
reply packet header: Connection reset by peer
postfix/smtpd[22871]: warning: milter
unix:/var/spool/MIMEDefang/mimedefang.sock: read error in initial handshake

Afterwards, with _all_ the following client connections I get this error:

postfix/smtpd[23199]: warning: connect to Milter service
unix:/var/spool/MIMEDefang/mimedefang.sock: Connection refused

The socket still exists, the rights are correct. I have to restart MD to
get the whole system working again.
On another system with MD 2.67 and the same Postfix version this does
_not_ happen.

Any ideas or hints?
Thanks!

regards
Stefan