gary c new siedpufbyahoocom 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 assistance greatly appreciated respectfully gary fri 08 aug 2008 025652 0800 challenging local senderrecipient spam