mouss qpeqrnetoyennet robert fitzpatrick wrote tue 20080226 1925 0100 mouss wrote general aware consume lot smtpd processes verification slow slow destinations called verification checks lead reject sav instead sav consider spamblocker greylisting use sav selective accounts senderdoamins insist sav option raise limit smtpd process use verify probes default smtp well risk blacklisted abuse reliable way tell prober sav list washing participating distributed slow dictionary attack transport destinations control need gateway know user exists hand reduce filter load make sure customers transport server make sure server let us know asked possible restrict smtp us still stand chance abuse issues think still need selective known transports use reject_unverified_sender dont seem need careful sender forged joe job storm system must particpate dosing forged sender mta never sent mail domain probe hard domain admin know side also impossible know whether dosed sort distributed dos also since people disable vrfy one argue dont want people verify addresses without sending mail sav safe agreement remote domain may acceptable results allowing legitimate mail would rejected otherwise sort whitelisting envelope informations look suspicious dont think real use case well since getting correct reject code 550 set guess getting hammered request fri 08 aug 2008 041221 0100 number rejections exploded