Open Source Linux Mail Transfer Agents

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, calendaring, and mailing list services.

E-MailRelay is a simple SMTP proxy and relay MTA, written in C++, for Linux and Windows. As a proxy all messages can be passed through a user-defined program, such as a spam-filter, which can drop, readdress, or edit messages as they pass through.

mailsend is a simple command line program to send mail via SMTP protocol. It can send a piece of alert mail from a program in a networked Windows machine. It's feature-filled, cross-platform, free and open source, and does not use any config file.

Highly scalable/configurable Messaging Platform allowing users in a domain to be distributed on multiple hosts, has multiple queues. Provides virtual domains/users in MySQL. Modern MSP class qmail replacement with ESMTP, POP3/IMAP, QMTP, QMQP support

ZMail allows you to send email from anyone, to anyone. You can use ZMail to send fake or anonymous emails. Have fun!

Moved to GitHub → https://github.com/yoctobyte/visualsynapse --- Visual Synapse are component wrappers around the Synapse tcp/ip libraries. It wraps a few common internet protocols, like HTTP, UDP, DNS, ICMP, TCP and SMTP to multi-threaded components that can be used with Delphi, Kylix, Freepascal and C++ Builder.

ESMTP MTA is a user configurable relay-only MTA with a sendmail-compatible syntax, based on libESMTP and supporting the AUTH (including the CRAM-MD5 and NTLM SASL mechanisms) and the StartTLS SMTP extensions.

jwSMTP, Send email programmatically (C++ code/lib). Linux, BSD, Windows etc. Attachments, Multiple recipients, Cc/Bcc recipients supported. MX lookup or send to an SMTP server direct. LOGIN and PLAIN authentication now supported. Html or plain text forma

Provide an Open Source Java Email Server that supports POP3/SMTP.

MailArchiva is a powerful, full featured email archiving (email archiver) and compliance solution for mail systems such as Microsoft Exchange. It stores all incoming, outgoing and internal emails for long term storage. A web based user interface is avail

YPOPs! is an application which emulates a POP3/SMTP mail server and provides free POP3 and SMTP access to Yahoo! Mail. It does not depend on Yahoo's POP3/SMTP mail server. You can use a mail client of your choice!

KumoMTA is an Open-Source, enterprise-grade email message transfer agent (MTA) software for sending high-volume, business-critical emails. KumoMTA is typically chosen by high-volume email users looking to replace PowerMTA, Momentum, or traditional Open Source MTAs. KumoMTA offers high-performance message relay to the tune of millions of messages per hour per server, combined with extreme flexibility and configurability through its use of a Lua scripting engine for configuration and message management.

Python API for Sendmail Milters. Related modules provide features such as content filtering, SPF, and reputation tracking. Changes are posted first to https://github.com/sdgathman/pymilter and related repos.

An SSL Postfix Management Interface in PHP/Ajax that handles all postfix parameters including Virtual Domains in LDAP.It handles all securities features by implementing all addons like Spamassassin,Clamav,Milter-greylist,amavis within technical skills

NetPop -- a Netscape / AOL Email Popper written in Java, much like YPOPs! for Yahoo mail and Mr Postman for Hotmail, that allows anyone to use a POP3 email client (Thunderbird, Eutora, Outlook, etc) with Netscape and AOL webmail.

PyWebMail is a Python library and POP3 gateway that enable working with WebMail servers like with POP3 or IMAP mail server. Currently Mail.Com, Yahoo! Mail, Gmail, Netscape.Net, HotMail and some minor servers support is finished.

hotwayd/hotsmtpd are POP3/SMTP-HTTPMail gateway daemons. The HTTPMail protocol is used by the mail servers Hotmail, Lycos, Spray and MSN. The hotway suite you can receive and send mail via these services using any POP3/SMTP compliant mail reader.

Jamm (Java Mail Manager) is a web application to manage virtual email account information stored in an LDAP directory. It is meant as an administration tool for sites using mail servers, such as Postfix and Courier-IMAP.

Mail2sh is a tool for send shell command by email with a simple module and to avoid you to know how procmail and sendmail works. Mail2sh makes it possible to carry out shell commands by email. Email is sent to a particular user on your host and the commands will be carried out if the user and password given matches ones in /etc/passwd. Commands are executed with the user's privileges, and combined with a PGP module ensures a certain level of security for use. Note that the system is not natively encrypted, so use of an encryption mechanism is highly recommended for security reasons.

This program rapidly delivers bulletins by linking them to a single bulletin file. This saves heaps of disk space and is >100 times faster than regular delivery.

Mailfilter to secure maildrops while fetch mails from a remote mail server and prevent mailloops, unwanted resend to external receipients and/or virus and spam.

Smtp Relay Checker is a network open mail relay checker. It is muti-threaded so it can be used to scan vast networks quickly, it is fully configurable so it can be adjusted to suit any need, and the scan results can be displayed in HTML. It is intended f

A small SMTP Server that is easy to use and allows for virus and SPAM checking.

This is a module PostNuke for those who like to give emailforwarding to their users. It simply allows users to make/edit a .qmail-{pn_uid} file in a directory (configured by the siteadmin).