Posted inpostfix
Postfix Selective Sender Addresss Verification
The idea is selectively probe valid email sender for certain domain that frequently forged by spammer, we should use sender access verification carefully. Much better if we noticing postmaster/admin that we conducting SAv/probing their server for valid user, or otherwise we’ll end up in backscatterer.org list hehehe…
Create smtpd_restriction_class call verify_sender
smtpd_restriction_classes = verify_sender
Define verify_sender so it should reject all unverified email sender, verified one will be permit/pass
verify_sender = reject_unverified_sender, permit
Create has table called frequently_forged_senders to define sender domain that going to be in verification list
check_sender_access hash:/etc/postfix/frequently_forged_senders
frequently_forged_senders contains
domain1.tld verify_sender domain2.tld verify_sender domain3.tld verify_sender
