VMailer is Wietse Venema's attempt to provide a freeware alternative to the widely-used Sendmail mail transport agent. The project goal is to be compatible at the user level, and to improve on Sendmail's performance, ease of configuration, reliability, and security.

Wietse Venema is the author of widely-used software such as the TCP Wrapper tool for network monitoring and access control, and is the co-author of the notorious SATAN network scanner. After a training as a nuclear physicist, he expanded his information technology skills at Eindhoven University. Wietse is currently a research staff member at the IBM T.J. Watson Research Center.