Fixes the problem of bad email 'Return-Path' header settings which prevent email bounce backs going to the sender
of the email.
Most mail servers appear to over-write any 'Return-path' headers sent by the PHP mail() function.
The 'Return-Path' value is used by some mail servers to send bounce back emails. A lot of web hosting companies send emails out with a return-path email based on the account name Apache runs as on the server, e.g. email@example.com or firstname.lastname@example.org
One solution is to define the -f sendmail parameters in the php.ini 'sendmail_path'.
This is no good when running a single Apache instance with PHP as there is only one php.ini and you need to specify different return addresses for each domain.
This module resolves the problem by parsing out the return-path set by Drupal modules, and passing it to the sendmail binary using the -f option, rather than sending it only in the $headers parameter of the mail() command.
Developed by Ixis