PowerMTA - PowerMTA is an industrial-strength software for high-volume email delivery.
turboSMTP - turboSMTP is a reliable, powerful, easy-to-use SMTP server that maximizes the deliverability of all...
Postfix - Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.
SMTP - SMTP provides scalable affordable email infrastructure for all your sending needs.
Sendmail - Sendmail is a general purpose internetwork email routing facility that supports many kinds of...
Postmark - Postmark is the easiest and most reliable way to be sure your important transactional emails get to the inbox. Simply & reliably parse recieved email to JSON for your webapp.