Funnily enough, Gmail can be on the receiving end sometimes too, e.g. being blocked in SORBS. The response was: 451 Currently Sending Spam See: http://www

Funnily enough, Gmail can be on the receiving end sometimes too, e.g. being blocked in SORBS. The response was: 451 Currently Sending Spam See: http://www.sorbs.net/lookup.shtml?209.85.215.41 Although some may argue that SORBS is a bad system, anyway.