Postfix

Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail. It attempts to be fast, easy to administer, and secure. The software is also known by its former names VMailer and IBM Secure Mailer.

Free Open Source Mac OS X Linux

Courier-MTA

The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP, SSL, and HTTP.

Free Open Source Mac OS X Linux BSD Self-Hosted

MailerQ

MailerQ is a high performance Mail Transfer Agent (MTA) and a very fast SMTP server, designed to deliver large volumes of email messages at very high speeds. MailerQ is...

Commercial Linux

Dragonfly Mail Agent

a small mail transport agent (mta), designed for home and office use. part of http://alternativein .

Free Open Source Linux BSD

Sendmail

Sendmail is a general purpose internetwork email routing facility that supports many kinds of transfer and delivery methods, including the Simple Mail Transfer Protocol (SMTP) used for email transport over the Internet.

Free Open Source Mac OS X Linux

OpenSMTPD

OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with some additional standard extensions. It allows ordinary machines to...

Free Open Source Linux BSD Self-Hosted

Hectane

An SMTP client that is extremely easy to configure and use, providing a simple HTTP API that is used for sending emails.

Free Windows Linux

Haraka

Haraka is an open source SMTP server written in Node.js which provides extremely high performance coupled with a flexible plugin system allowing Javascript programmers...

Free Open Source Self-Hosted Node.JS

Microsoft SMTP Server

Configure SMTP e-mail in IIS when you want to deliver e-mail messages from your site. Mail can be delivered immediately or it can be delivered to a file location on disk...

Commercial Windows

sSMTP

sSMTP is a simple MTA to deliver mail from a computer to a mail server. sSMTP is simple and lightweight, there are no daemons or anything hogging up CPU; Just sSMTP....

Free Open Source Linux

PowerMTA

Email gateway application (SMTP server) that makes it easy for senders to adopt the latest authentication specifications ( SPF and DKIM) to comply with changing ISP...

Commercial Windows Linux Self-Hosted

BulkMTA

BulkMTA is Commercial Mail Server Similar to PowerMTA. IP Rotation, DKIM, Sender / Receiver Rate limiting

Commercial Mac OS X Windows Linux

EmailSuccess

EmailSuccess, an advanced SMTP Server (MTA) built from the ground up to handle the most critical reliability, performance, security, and deliverability requirements.

Commercial Linux