thomas ledbetter htjdyuacrevelstonenet never ending quest block spam get performance mx server postfix configuration tried lowering smtpd_hard_error_count value weve great success past lowering smtp_timeout parameter seemed like another interesting tactic try setting smtpd_error_count lower value immediately saw number messages blocked many errors rise expected analyzing blocked seem like spam stopped however hour situation load average mx servers rapidly started climb necessary revert previous values im thinking messages getting rejected 4xx error code simply queuing remotely overwhelming us resent later make sense looking postfix configuration parameters although saw change reject code things didnt see smtpd_error_reject_code parameter like one go changing error code 5xx type rejects caused many errors possible reason bad idea tue 05 aug 2008 191317 0500 smtpd_error_reject_code