Re: Restricting Senders Ki Song wrote:
> I changed these settings in the main.cf file and restarted postfix.
> Still, we're getting "hammered" by some spammer that is sending tons of
> emails from cphur@visa.com
>   

from where? outside or inside? if it's an insider, your best approach is 
to enforce authentication. if it is an outsider, then you can't require 
that _we_ use your domain in _our_ sender addresses.
> Is there a way to disallow messages from cphur@visa.com?
>
>   

when you have a problem, always show relevant logs so that other people 
can see other ways to help you. blocking a sender is not the right 
approach. you need to look at other patterns. which is why relevant logs 
are needed.

anyway, consider using
    reject_rbl_client zen.spamhaus.org
this should reduce your spam load.


