text_combined: mouss qpeqrnetoyennet gary c new wrote issue spammers making raw socket connections postfix server spoofing one mynetworks domains server deliver valid recipient mynetworks domain smtp auth configured working method spamming unchallenged due viewed valid mynetworks domain best way postfix challenge method spam weve already explored reject_sender_login_mismatch feature aggressive environment essentially need ensure sender smtp authed sending message regardless valid mynetworks domain use reject_unauthenticated_sender_login_mismatch applies unauthenticated mail fri 08 aug 2008 144120 0100 challenging local senderrecipient spam