I have the following "problem" for which I'd need hints.
I use exim 3.36 with several domains (50 or so).
I like to reject spam at smtp time to avoid unnecessary
overload of the server. Of course I use RBL lists, but
I still receive quite a number of spam. Some for non-
existent users in domains such as ceo@ and president@
nowadays. I tried to use receiver_verify but since I
also use Mailscanner, the "receiving" exim only defers
the delivery for everybody, therefore receiver_verify
is not usable because it would reject every mail then.
Bonus question: "clever" spammers address our secondary
mail server, which only relays all of our domains to the
primary server so at that point it is not really possible
to tell whether a local-part is valid or not. Then, - of
course - at our primary mail server, it is unwanted to
bounce the crap back to our secondary one.
Any "Ultimate Solution (tm)" or something close to it,
anyone?
