Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
PowerMTA - PowerMTA is an industrial-strength software for high-volume email delivery.
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
MailerQ - MailerQ is a high performance Mail Transfer Agent (MTA) designed for delivering large volume email messages at very high speeds.
Courier-MTA - The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open...
KumoMTA - KumoMTA is the world's first Open-Source MTA designed from the ground-up for large-volume senders. Get a fast, flexible, supported solution.