Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
MailerQ - MailerQ is a high performance Mail Transfer Agent (MTA) designed for delivering large volume email messages at very high speeds.
sSMTP - sSMTP is a simple MTA to deliver mail from a computer to a mail server.
turboSMTP - turboSMTP is a reliable, powerful, easy-to-use SMTP server that maximizes the deliverability of all...
OpenSMTPD - OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with...
SMTP - SMTP provides scalable affordable email infrastructure for all your sending needs.