Another sendmail relaying problem.

Craig White craigwhite at azapple.com
Sat Jun 26 01:10:38 UTC 2004


On Fri, 2004-06-25 at 13:10, Alexander Dalloz wrote:
> Am Fr, den 25.06.2004 schrieb Cowles, Steve um 21:32:
> 
> > Franco wrote:
> > > Sorry, i speach very bad english,
> > > i'm already installed spamassassin with clamav antivirus and
> > > all work fine i want block the e-mail sent through my smtp
> > > with mail from as one of my local user.
> > > 
> > 
> > I think I understand what Franco is asking. He wants to stop an external
> > sender (spammer) from setting their From: address to appear like its coming
> > from his domain space and then having his MTA accept this e-mail for local
> > delivery. 
> > 
> > Correct?
> 
> Maybe correct. I don't understand him neither too.
> 
> > BTW: By default, sendmail should NOT be relaying (as in open relay) to
> > anyone outside your domain space when someone sets their "From:" address to
> > be the same as your domain space. It should accept the e-mail for local
> > delivery only, unless overridden. Unfortunately, I don't remember how to
> > implement what your asking using sendmail. It's a piece of cake in postfix
> > though. Sorry!
> 
> It is plain default in Sendmail. As long as you don't misconfigure
> Sendmail it won't relay based on mail addresses, as that is evil foo!
> You just can't prevent that someone foreign sets his mail address to be
> from your domain. You will then get bounces by not well configured mail
> servers. Impossible to prevent. It's a matter of SPAM fighting to handle
> that proper.
----
Isn't it almost certain that he is referring to various Windows viruses
that use Outlook/Outlook Express addressbooks to forge 'from' addresses
and identify 'to' addresses and his question has nothing to do with
sendmail at all?

What about the headers of those 'emails' and the mail server logs?

Craig





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