I'm doing some more thinking about this, and trying to follow the flow of the mail and the probes.
Starting at the front, right now I have a postscreen instance on 'mail1'. It listens to inbound mail then passes mail to amavisd [mail1.example.com]:25 inet n - n - 1 postscreen -o smtpd_service_name=psint psint pass - - n - - smtpd -o syslog_name=postfix/psint -o smtpd_proxy_filter=127.0.0.1:30000 -o smtpd_authorized_xforward_hosts=127.0.0.0/8 ... I want the remote address verification to be done BEFORE passing to amavisd. So if the verify fails because the recipient address does NOT exist when checked by 'mail1' at the 'mail2' server, then the mail should be rejected Even though I have the address_verify_transport_maps = static:addressverify:[mail2.example.com]:25 it doesn't look like it's actually checking the remote for recipient address verification; instead it's just failing. So taking a step back, how do I make sure that the remote address verification occurs after postscreen, but before the proxy filter pass to amavis?