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Subject: Re: reject_unknown_sender_domain - still relevant?
From: Greg Stark (gsstarkmit.edu)
Date: Sun Feb 06 2000 - 15:18:23 CST

jseymourjimsun.LinxNet.com (Jim Seymour) writes:

> In message <20000206212029.A6527tirad.internal.iphil.net>,
> dated Sun, 6 Feb 2000 21:20:29 +0800,
> "Miguel A.L. Paraz" <mapiphil.net> wrote regarding the subject
> "reject_unknown_sender_domain - still relevant?":
> >
> > Hi all,
> >
> > I note that the vast majority of "Domain not found:" messages due to
> > 'reject_unknown_sender_domain' are from misconfigured sender mail systems, or
> > misspellings in user MTA's.
>
> Then, IMO, they should fix them. I see no particularly good reason
> to cripple my MTA for the purpose of encouraging their incompetence.

Is this a transient error or a permanent error? If it's a permanent error then
I suggest your system is broken. It means that if your DNS server goes down or
if there's a major internet partition and you can't reach the outside world
then you'll reject all incoming mail with permanent errors.

A transient error does make sense here. In fact one suggested anti-spam
mechanism was to give transient error messages for all messages and cache the
envelope information. Then accept it the second time through. This is on the
theory that spammers generally don't ever retry whereas real mail will. 

-- 
greg