[Gllug] Handling a new twist by spammers

[Andrew Halliwell]

> One of my machines functions as a secondary mail server (running Exim). 
> I notice this morning that it has a large number of frozen messages and
> looking at them I find a new twist to the nuisance of spammers.
> 
> Someone has been sending a large number of e-mails to randomly generated
> addresses, (like "fred101 at linuxemporium.co.uk",
> "fred102 at linuxemporium.co.uk" etc.) and then sending them to the
> *secondary* mail server.  It accepts them because it doesn't know any
> better, then tries to pass them on, fails, tries to send them back to
> the originator, fails again and then freezes them.
> 
> It looks either like incompetence or a half-baked DoS attack.  Is there
> anything that can be done to prevent this trick?

Block all mail not coming from your domain or that of the ISP's "smarthost"?

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