Microsoft SMTP Server!

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. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list services within a single, consistent, framework. Individual components can be customized, enabled or disabled at will.

Atmail webmail system offers a webmail client, email server platform and mailserver appliance for Linux, Unix and Windows.

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. A descendant of the delivermail program written by Eric Allman, Sendmail is a well-known project of the free and open source software and Unix communities, and has spread both as free software and proprietary software.

A small Mail Transport Agent (MTA), designed for home and office use. Part of DragonFly BSD , it accepts mails from locally installed Mail User Agents (MUA) and delivers the mails either locally or to a remote destination. Remote delivery includes several features like TLS/SSL support and SMTP authentication. dma is not intended as a replacement for real, big MTAs like Sendmail or Postfix. Consequently, dma does not listen on port 25 for incoming connections. »

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

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 exchange e-mails with other systems speaking the SMTP protocol.

AtMail is an open source webmail client written in PHP. We aim to provide a elegant Ajax webmail client for existing IMAP mailservers, with less bloat and a focus on an intuitive, simple user interface.

SSMTP is a program which delivers email from a local computer to a configured mailhost (mailhub). It is not a mail server (like feature-rich mail server sendmail) and does not receive mail, expand aliases or manage a queue. One of its primary uses is for forwarding automated email (like system alerts) off your machine and to an external email address.

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

Powerful and simple SMTP/POP3/Finger server, with built in Web interface for accessing mail via Web browser. Supports security features, such as SMTP authentication. Has built-in TZO client for users without static IP address. Version 1.8.8.8 may include unspecified updates, enhancements, or bug fixes.