Whenever this module is enabled (not necessarily activated), emails send via Drupal that bounce may NOT return to the sender (depending on the hoster).
The Return-Path module solves this issue, but it is incompatible:
http://drupal.org/node/98412#comment-2122988
Comments
Comment #1
not_Dries_Buytaert commentedSorry, my bad. It turns out the return path IS (!) handled correctly by the 'SMTP Authentication Support' module after all.
This module only is incompatbile with the 'Return-Path' module, whenever they are installed and activated at the same time.