Blocking spam based on from address

[Julian Field]

Michael Masse wrote:
> Since we are using MS as a relay there is never a case where mail
> destined to a user within our domain will ever be from another user
> within our domain because that all happens internally within Groupwise. 
>   The only email that goes through MS that truthfully has a from address
> of our domain is outgoing email.   Since MS calls sendmail, can MS tell
> sendmail to drop all email claiming to come from our domain unless it
> actually is, or is this something that I have to do at the MTA level?   
>   
You could use a ruleset for "Reject Message" saying something like
From: yourdomain.com and 152.67. no
FromOrTo: default yes

That way only mail whose sender is user at yourdomain.com and comes from 
the 152.67. network is allowed through.
All other mail is rejected with a nice polite message.

You could better apply this ruleset is "Is High Scoring Spam" instead so 
that you can just drop it with a "delete" action rather than send a 
bounce message, which is very bad practice.

-- 
Julian Field
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