grep filters to block open relay

[hermit921]

At 04:31 PM 3/23/2006, Kai Schaetzl wrote:
>Hermit921 wrote on Thu, 23 Mar 2006 14:28:23 -0800:
>
> > They can't or won't configure Exchange to accept mail only if the
> > recipient address is valid
>
>AFAIK, Exchange *can* be configured to not be an open relay.
>
> > user%ibm.com at sun.com
>
>The relay tests don't work this way. They will try to send email with some
>tricks to addresses that are not on your machine. This includes tricks
>like the above. But accepting and dropping such a mail will possibly not
>get you on such a list. Only if that mail is received in their spamtrap
>then you qualify as an open relay, just accepting and not forwarding it is
>fine.
>
>Kai

The actual address (slightly edited) used was
"marvin at marvin.tester.org"@mydomain.com
and that mail got returned to the sender at tester.org.  Therefore it is an 
open relay.

What the Exchange admins did (after they got listed as an open relay) is 
reject any message that matches some character pattern that would catch 
this email address.

Don't ask me how silly this is - I feel like screaming.
I just want to know if anyone else has ever heard of this type of filtering 
being done.

hermit921