Comment 4 for bug 776753

I'm affected after a recent upgrade to natty too, though a little differently.
In syslog i was getting a lot of:
MailScanner: Process did not exit cleanly, returned 9 with signal 0

Which after starting with debug = yes gave me;
Insecure dependency in open while running with -T switch at /usr/share/MailScanner//MailScanner/Lock.pm line 358.

This seems to be related, and the workaround in http://lists.mailscanner.info/pipermail/mailscanner/2011-April/097813.html
"adding the -U switch in the showbang line in /usr/sbin/MailScanner." works.