MTA preferences for use with MailScanner

[Julian Field]

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At 15:45 29/07/2004, you wrote:
>Allow me to paste fro the Postfix archives:
>------------
>MailScanner does its work by grabbing files out of the queue, runs its
>processing, and drops the resulting file back into another postfix
>queue.  This is not a documented method to perform content filtering in
>postfix.

It's not documented in Exim either. But the guys who wrote Exim run
MailScanner. The sendmail guys just did the honourable thing and documented
the whole process, they have nothing to hide.

>The problem is that there is no reliable way for a non-postfix program to
>determine when it's safe to grab the queue file.  So it's never safe for an
>external program to grab a queue file when postfix is running.

So Postfix does a secret-squirrel handshake or something? It's code, it's
deterministic.

>So MailScanner will randomly grab an incomplete file,

Simply not true.

>  resulting in loss of
>a random portion of that message,

Also not true.

>  with no warning and no indication that
>part of the message was lost.

Also not true.

>   Apparently it *usually* works, but you can't
>tell when it doesn't.  Software that by design *usually* works is not
>acceptable.

Except when *usually* = 100%.

>Therefore, MailScanner is unreliable with postfix.  This does not offer an
>opinion about MailScanner with other MTAs, only postfix.

I'm sorry, I thought "outside the box". Please accept my apologies for not
using your (relatively slow) "approved" way of doing things, and coming up
with a novel idea you didn't think of.

>If you want to use MailScanner, don't use postfix.

There are plenty of faster MTA's out there, such as Exim or ZMailer, so I
would personally agree with this statement. But not for the same reasons
they are saying it.

>   If you want to use
>postfix, choose a different content filtering method, there are several
>documented filtering methods and many reliable third-party products to
>chose from that work properly with postfix.
>------------
>
>However, it works for me, so what can I say.

Precisely.

As you may have gathered, there is no love lost between me and Wietse. But
then again, from what I have heard from some of his previous colleagues,
I'm not the only person in that situation :-)
--
Julian Field
www.MailScanner.info
Professional Support Services at www.MailScanner.biz
MailScanner thanks transtec Computers for their support
PGP footprint: EE81 D763 3DB0 0BFD E1DC 7222 11F6 5947 1415 B654

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