On May 16, 2012, at 12:21 PM, Brian Evans - Postfix List wrote: > On 5/16/2012 2:07 PM, James Lay wrote: >> On May 16, 2012, at 9:42 AM, Ansgar Wiechers wrote: >>> The answer to that question can be found in "man 5 transport". >>> However, you don't want to mess around with a reject-users table in >>> the first place (particularly not as a transport map). Instead just >>> change your smtpd_recipient restrictions like this: >>> smtpd_recipient_restricitons = permit_mynetworks >>> reject_unauth_destination reject_unlisted_recipient ... As Brian >>> already explained, it's the default to reject undefined recipients, >>> so you wouldn't need to do anything (unless you have configured a >>> catch-all somewhere, which you shouldn't). However, I consider it >>> good practice to reject mail for invalid recipients early on (before >>> doing more expensive checks), which is what the >>> reject_unlisted_recipient restriction is for. Regards Ansgar Wiechers >> Thanks Ansgar, >> >> I was under the impression that DISCARD was better then REJECT due to >> backscatter? We get hundreds of crazy emails to things like >> ya64s...@mydomain.com, so I opted for DISCARD instead. I'll do some more >> reading and see how I can get this to fly. Thanks again. >> > > Definition according to Wikipedia: > Backscatter (also known as outscatter, misdirected bounces, blowback or > collateral spam) is incorrect automated bounce messages sent by mail > servers, typically as a side effect of incoming spam. > > Backscatter occurs when you ACCEPT the message on the front end and then > generate a bounce because it cannot be delivered. > > You want to flat out reject what you cannot deliver, that is the correct > way to handle things. > If malware, bots, or other trash is sending it, no one cares because > your system will NOT generate a bounce. > If it is a legitimate message, the SENDING MTA will bounce back to its > user for notification. > In some countries, I hear that it is illegal to discard email and reject > is the only option. > > Brian
Awesome…thanks for the clarification Brian. James
