A typical web application sends out mail but doesn't check for the validity of the mail address causing lots of bounces.
This is undesirable since it causes overhead for the web at large and can also lead to the webserver being blocked by receiving MTAs and/or the mails getting a higher spam rating leading to less successful mail delivery.
This module contains a drush script that is meant to be called by the MTA when it receives a bounce.
It will expect a VERP encoded delivery address from which the user address is extracted.
Incoming bounces will be collected in the database and can be reviewed by an admin.
A admin UI is provided to potentially disable accounts or subscriptions for bouncing mail addresses.
In order to use this module you will need to be able to configure your MTA to some degree.