postfix: Process did not exit cleanly, returned 1 with signal 0

[Dave Jenkins]

Hello,

I'm new to the list . I have successfully run MailScanner with
sendmail for a couple of years, now setting it up with postfix on
another server.

MailScanner & postfix have mostly been running happily for a few
weeks, averaging about 5 msgs/min. But on two occasions we've had
defunct MailScanner processes and the error "postfix: Process did not
exit cleanly, returned 1 with signal 0".

Once the error & the defunct processes started appearing, there was an
ever-growing "Found N messages waiting" (got to 480 first time) and no
mail getting through. /var/log/maillog revealed that the same batch of
30 messages was being scanned over & over.

Disabling virus scanning in MailScanner.conf, didn't help. Neither did
removing all "yes" entries from
/etc/MailScanner/rules/spam.checking.rules, leaving default "no". (I
restarted MailScanner after each change.) Finally I turned off
scanning (Scan Messages = no) and this allowed the queue to clear.

I then switched scanning, virus and spamassassin back on (i.e.
restored previous config) and it then ran fine. I'm wondering if it
was a peculiarity of one of the messages that caused MailScanner to
crash.

The second time it happened, before clearing the queue I took a copy
of /var/spool/MailScanner/incoming; will that help in debugging the
problem? If so, what should I do with it and if not, what should I do
next time it happens?

Software:
Centos 5
postfix-2.3.3-2
mailscanner-4.69.8-1 from rpm from mailscanner.info
clamav-0.93-2.el5.rf
spamassassin-3.1.9-1.el5

Hardware:
CPU: AMD Phenom(tm) 9550 Quad-Core Processor
RAM: 2G
DIsks: 2 x 500GB SATA in software RAID-1

Thanks,
Dave.