Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
Sendmail - Sendmail is a general purpose internetwork email routing facility that supports many kinds of...
Exim - Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.
blat - Blat is a small, efficent SMTP command line mailer for Windows.
OpenSMTPD - OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with...
sendEmail - sendEmail is a lightweight, command line SMTP email client.