On May 9, 2008, at 6:15 AM, Joseph Brennan wrote: > Forget SPF. Why should any system accept mail for an unknown > recipient > and then mail a bounce? That's the primary cause of backscatter. > These > systems are just as likely to accept the message, then check SPF, and > mail a bounce :-) There are a number of different systems that try to be smart about when to send back a bounce message. Pretty much every MLM besides Mailman includes logic attempting to return valid syntax errors to senders, but avoid backscattering people. SPF is obviously part of that equation. And it does help fairly significantly in practice. We have some wide open/non-filtered mailboxes that we are required to run. Implementing SPF on those mailboxes reduced our backscatter by about 24% instantly, which was just under 500 messages a day. -- Jo Rhett Net Consonance : consonant endings by net philanthropy, open source and other randomness ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
