Fast, highly extensible, and event driven SMTP server.

Complete trashmail solution that exposes an SMTP server and has a web interface to manage received emails. Works with multiple and wildcard domains and is fully file based (no database needed). Includes RSS feeds and JSON API.

A small MTA for home and office use. Works on Linux and FreeBSD.

SMTP (email) server with a focus on simplicity, security, and ease of operation.

Fast, scalable, enterprise mail/groupware server providing ESMTP, IMAP, POP3, webmail, mailing list, basic web-based calendaring and scheduling services.

A small and easy to configure SMTP and POP3 server for Windows and Linux.

Message transfer agent (MTA) developed at the University of Cambridge.

Secure SMTP server implementation from the OpenBSD project.

Fast, easy to administer, and secure Sendmail replacement.

Message transfer agent (MTA).