>> I don't know if other MTAs support sender verification but if they >> don't they should. It's a very good trick for blocking spam at connect time. > > It's also a good trick to cause a denial of service.
You think so? By my count, my server is transmitting roughly 80 bytes of data (HELO, MAIL FROM:, RCPT TO: and QUIT); even with overhead from RBL checks on your side that shouldn't contribute to any load. It's not like an evil spammer could carefully synchronize it so that millions of mail servers would all try to do callouts at exactly the same microsecond, after all. Have you actually seen a server DOSed by sender callouts, ever? I never have and I've ever heard of one.... -- Dave Pooser Cat-Herder-in-Chief, Pooserville.com "And the beer I had for breakfast Wasn't bad, so I had one more for dessert."
