Exim If you are having problems changing the Sender and Return-Path headers, make sure that you are editing the right configuration file. On my CentOS 5.6: [root@server mail]# ll /usr/sbin/sendmail lrwxrwxrwx 1 root root 21 Oct 26 2009 /usr/sbin/sendmail -> /etc/alternatives/mta [root@server mail]# ll /etc/alternatives/mta lrwxrwxrwx 1 root root 23 Apr 9 07:48 /etc/alternatives/mta -> /usr/sbin/sendmail.exim [root@server mail]# ll /usr/sbin/sendmail.exim lrwxrwxrwx 1 root root 4 Apr 9 07:45 /usr/sbin/sendmail.exim -> exim I spent some time trying to figure out why my changes to the sendmail.mc file were being ignored. Naturally, Exim configuration is different than Sendmail. You need to edit the /etc/exim/exim.conf file: remote_smtp: driver = smtp return_path = bounce@domain.com headers_rewrite = apache@* info@domain.com s Don't forget the "s" at the end. See this page for more information: http://www.exim.org/exim-html-2.00/doc/html/spec_32.html...