Postfix and duplicate mails

[Keith Edmunds]

Hi

I've been using MailScanner with Postfix for a couple of months, largely
successfully. However, I have had a few duplicate deliveries where the first
message contains only the headers and the second copy is the complete
message. The headers for both messages are completely identical.

Looking on Google I found a thread on mailing.postfix.users entitled
"Postfix/Mailscanner truncated messages" (the rather long URL to see this on
Google is
http://groups.google.co.uk/groups?hl=en&lr=&ie=UTF-8&threadm=biilhp%242o0e%241%40FreeBSD.csie.NCTU.edu.tw&rnum=1&prev=/groups%3Fq%3Dmailscanner%2Bpostfix%2Bduplicate%26hl%3Den%26lr%3D%26ie%3DUTF-8%26selm%3Dbiilhp%25242o0e%25241%2540FreeBSD.csie.NCTU.edu.tw%26rnum%3D1)

This thread discusses the same problem I am seeing, but also has comments from
Wietse Venema, the author of Postfix, as follows:

"mailscanner can result in random loss of email when moving queue
files between Postfix queues in different file systems. This breaks
the guarantee of queue file name uniqueness.  Different messages
can get the same queue file name and one of them will be lost.

mailscanner also introduces all kinds of race conditions when moving
files between Postfix queues in different file systems. This may
explain why the other guy was seeing delivery of incomplete email
messages."

This is (obviously) a concern to me. Postfix does have some support for
using external filters, etc: is it possible for MailScanner to be hooked
into Postfix using that mechanism? Or is there another way?

Thanks,
Keith