On 2011-May-25 18:09, Eric J Esslinger wrote: [..] > Does anyone know of a way for me to block the following, using > postfix, either via refusing to accept the mail or by dropping it in > /dev/null: Mail from <> or postmaster that originates within our > customer IP blocks/is sent using authentication at the submission > port and/or that does not have a valid local recipient.
http://www.postfix.org/header_checks.5.html But you should be lucky your customers are actually using your SMTP relay in the first place instead of just bouncing directly to the target MX. Greets, Jeroen
