On 2011-06-09 Wiebe Cazemier wrote: > I was setting up a fallback MX server with Postfix and was struggling > with preventing backscatter mail. I thought I found a good solution, > but it turned out to be an illegal option. > > Postfix has the ability to do recipient address verification. When > postfix acts as a relay server, this prevents backscatter mail > (bounces of messages because the server that is relayed to doesn't > accept the user). Backscatter is usually caused by spam of course, > because spam is sent to all kinds of users @example.com. > > I had in mind to use recipient address verification to avoid that and > then set "unverified_recipient_tempfail_action = permit". The idea > behind this was: > > - Prevent backscatter mail when the primary host is up because every > address is verified first. > - Accept all mail when the primary host is down, so that incoming > messages aren't deferred.
Why? What issue in particular do you see with simply doing recipient verification (and rejection of messages to invalid recipients) on bot MXs? Regards Ansgar Wiechers -- "Abstractions save us time working, but they don't save us time learning." --Joel Spolsky
