A Better E-Mail Bouncer

This paper describes a portable electronic mail bouncer which sends detailed information back to the sender when a mail message can not be delivered to it’s intended recipient. The bouncer was originally written to handle a large merger between multiple DNS domains, and is implemented entirely in Perl5 as a mail delivery agent. The bouncer operates under the concept of "least privilege" so it’s safe to run directly from mail transport agents such as sendmail. The bouncer is designed to make the human processes and interactions in dealing with undeliverable E-mail easier for both postmasters and end-users alike.