Spam fighting tools

[Henry Spencer]

On Tue, 6 Apr 2004, Fraser Campbell wrote:
> > ...Spammers and viruses both forge
> > "From:" *AND* envelope-sender.  On the other hand, if you send a 5XX
> > reject at the SMTP transaction, that's OK, because it doesn't contribute
> > to mailbombing innocent third-parties.
> 
> Unless I'm missing something the 5xx would still result in a message going to 
> the forged sender address.

The 5xx is part of the SMTP protocol itself.  So it's seen on the guilty
machine that's actually trying to send the mail, not the innocent one
named on the envelope etc.  The spammers are not going to waste their
machine resources by trying to do anything about it. 

                                                          Henry Spencer
                                                       henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org

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