James - Enterprise Mail Server

•    Java

James (a.k.a Java Apache Mail Enterprise Server) is a 100% pure Java SMTP and POP3 Mail server, and NNTP News server designed to be a complete and portable enterprise mail/messaging engine solution based on currently available open messaging protocols.

Zimbra - Email and Collaboration Suite

•    Java

Zimbra is the most capable open source email and collaboration suite available today. It provides support for Email, Shared calendar, Document management, Pop3, Address book and lot more. Mails could be tagged and search support is also provided. Zimbra is considered as an alternative to Microsoft Exchange Server.

Courier Mail Server

•    C

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.

deepOfix - Mail Server

•    C

The deepOfix Mail Server makes it possible for organisations with minimal technical expertise to have robust messaging infrastructure. It has built in LDAP support, SMTP, POP3 and IMAP services.

Ichabod Java Mail Server

•    Java

Ichabod is an SMTP/POP3 server, with mailing list support. Administration is via a web, or email You can also use Ichabod to make your app receive email as an SMTP server. You can also easily extend it by subclassing to add your own behaviors.

YPOPs! - POP3/SMTP Access to Yahoo

•    C++

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!

JavaMail - Java library to build Mail and Messaging Applications

•    Java

The JavaMail API is a set of abstract APIs that model a mail system. The API provides a platform independent and protocol independent framework to build Java technology based email client applications. The JavaMail API provides facilities for reading and sending email. Service providers implement particular protocols. Several service providers are included with the JavaMail API package; others are available separately.

Mailu - Insular email distribution - mail server as Docker images

•    Python

Mailu is a simple yet full-featured mail server as a set of Docker images. It is free software (both as in free beer and as in free speech), open to suggestions and external contributions. The project aims at providing people with an easily setup, easily maintained and full-featured mail server while not shipping proprietary software nor unrelated features often found in popular groupware. Most of the documentation is available on our Website, you can also try our demo server before setting up your own, and come talk to us on Matrix.

CRSMail - JAVA based E-Mail server

•    Java

CRSMail a 100% JAVA based E-Mail server. It supports SMTP, POP3, Plugins, Can listen on multiple ports, Log's everything to a log file etc.

C# Email Server - SMTP and POP3 Email Server in CSharp

•    CSharp

C# Email Server (CES). Implements SMTP and POP3 components that can be used as a standalone server or as components in other applications. It is a port of the Java Email Server (JES). This component allows a program to accept incoming emails and process them using user defined logic.

Openmeetings - Open Source Web Conferencing

•    Java

Openmeetings provides video conferencing, instant messaging, white board, collaborative document editing and other groupware tools using API functions of the Red5 Streaming Server for Remoting and Streaming. Meeting can be recorded and screen sharing support is also available.

Dovecot - Secure IMAP and Pop3 server for Linux

•    C

Dovecot is an open source IMAP and POP3 email server for Linux or UNIX-like systems written with security primarily in mind. Dovecot is an excellent choice for both small and large installations. It is fast, simple to set up, requires no special administration and it uses very little memory. Dovecot is NOT responsible for receiving mail from other servers. Dovecot presents mail already stored on the system to mail-user agents [MUA].

Kopano - Collaboration made easy

•    C++

Kopano Core provides the foundation for groupware messaging enabling clients such as Kopano WebApp, Kopano DeskApp, mobile and sync clients. With its modular architecture, Kopano Core enables the possibility for a variety of setup scenarios, scalable from a very low-powered system to a multi-datacenter setup providing messaging capabilities to tens of thousands of users.

Rumble Mail Server

•    C

Rumble is a mail server suite for SMTP (ESMTPSA), HTTP, POP3 and IMAP4v1 with an extensive C/C++ and Lua API for scripting. It comes with support for SSL/TLS, SQLite and MySQL and has a web-based administration and webmail feature. Additional included modules feature greylisting, DNS blacklisting, SpamAssassin support and dynamic performance scaling as well as a multithreaded structure that allows for clustering of multiple servers for one or all domains, and with the ease of the Lua API,

DavMail - POP/IMAP/SMTP/Caldav to Exchange

•    Java

DavMail is a POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway allowing users to use any mail/calendar client (e.g. Thunderbird with Lightning or Apple iCal) with an Exchange server, even from the internet or behind a firewall through Outlook Web Access. DavMail now includes an LDAP gateway to Exchange global address book and user personal contacts to allow recipient address completion in mail compose window and full calendar support with attendees free/busy display.

SharpWebMail - ASP.NET Webmail Application

•    CSharp

SharpWebMail is an ASP.NET webmail application that is written in C#. It uses a POP3 or IMAP servers as the mailstore and sends mail through a SMTP server. It is very simple to configure (only a few settings in the web.config file). You can compose HTML messages, search your inbox, read complex mime messages, have multiple address books and much more.

DotMail

•    CSharp

Since Microsoft is dropping the POP3 server from the next generation of Windows Server, I thought it would be a good idea to create a mail server that could utilize the SMTP server that is a part of IIS or any other SMTP server for that matter. The idea is to create a servi...

Claws Mail - Email Client and News Reader Based on GTK+

•    C

Claws Mail is a GTK+ based, lightweight, and fast e-mail client and newsreader. Supports POP3, APOP, IMAP, SMTP, SMTP AUTH, NNTP, LDAP, multiple accounts, spell-checking, addressbook, SSL, GPG, filtering, i18n, & more. It is further extended by plugins. Lots of extra functionality, like an RSS aggregator, calendar, or laptop LED handling, are provided by extra plugins.

smart messaging connector

Sending fax from a PrintDocument or a file. Sending broadcast fax. Managing (Pause/Resume/Restart) current fax job. Managing configuration of the fax server

Cola Bulletin Board System

•    Java

This is a Java implemented Bulletin Board System. Clients could use either Telnet or Browser to connect to this server. This system contains several servers: Telnet daemon, proprietary Java Applet C/S, NNTP Client to access News Server and SMTP C/S.