Postfix and duplicate mails

[Julian Field]

At 11:40 29/08/2003, you wrote:
>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.

This will be why I haven't been able to reproduce it. Clearly the incoming
and outgoing queues need to be on the same filesystem. I'll try to add a
"sanity" check for that in the Postfix initialisation code so that it
complains if this isn't the case.


>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

--
Julian Field
www.MailScanner.info
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