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Subject: Re: msn.com & service denial
From: Wietse Venema (wietseporcupine.org)
Date: Wed Jun 07 2000 - 18:44:08 CDT

Rask Ingemann Lambertsen:
> >As of version 2000whatever, Postfix will skip servers that greet
> >with 4xx/5xx by default. Too many sites assume that all the world
> >is sendmail.
>
> What were the good arguments? I think I have missed them.

The argument is that too many sites expect sendmail behavior.

The specific case that made me give up was the site whose primary
MX host greets with 5xx, and that expects to receive all outside
mail through its MX backups. Postfix would bounce the mail instead.
And since Postfix is supposed to be able to deliver mail where
sendmail can, it now defaults to ignoring [45]xx greetings.

I question the wisdom of those who configure an MTA to greet with
5xx and expect to receive mail via backup hosts, but sendmail allows
for such brain damage, people have gotten used to it, and now we're
stuck with it forever.

        Wietse