Free email software

free and open source email client and personal information manager

personal information manager software and workgroup information management tool for GNOME

Firefox derivative recommending only free software

Kontact is a personal information manager (PIM) and groupware software suite developed by KDE. It supports calendars, contacts, notes, to-do lists, news, and email. It offers a number of inter-changeable graphical UIs (KMail, KAddressBook, Akregator, etc.) all built on top of a common core.

text-based email client for Unix-like systems

Roundcube is a web-based IMAP email client written in PHP. It uses Ajax throughout its interface and is licensed under the GNU GPL version 3 or later, with exceptions for skins and plugins.

Zimbra Collaboration, formerly known as the Zimbra Collaboration Suite (ZCS) before 2019, is a collaborative software suite that includes an email server and a web client.

computer program for e-mail spam filtering

Enigmail is a data encryption and decryption extension for Mozilla Thunderbird and the Postbox that provides OpenPGP public key e-mail encryption and signing. Enigmail works under Microsoft Windows, Unix-like, and Mac OS X operating systems. Enigmail can operate with other mail clients compatible with PGP/MIME and inline PGP such as: Microsoft Outlook with Gpg4win package installed, Gnome Evolution, KMail, Claws Mail, Gnus, Mutt. Its cryptographic functionality is handled by GNU Privacy Guard.

GTK-based Email client

E-Mail application for Android

Exim is a mail transfer agent (MTA) used on Unix-like operating systems. Exim is a free software distributed under the terms of the GNU General Public License, and it aims to be a general and flexible mailer with extensive facilities for checking incoming e-mail.

email client

Sylpheed is an open-source e-mail client and news client licensed under GNU GPL-2.0-or-later with the library part LibSylph under GNU LGPL-2.1-or-later. It provides easy configuration and an abundance of features. It stores mail in the MH Message Handling System. Sylpheed runs on Unix-like systems such as Linux or BSD, and it is also usable on Windows. It uses GTK+.

SquirrelMail is an open-source webmail application written in PHP. It provides a web-based interface for accessing email via the IMAP protocol and sends messages through SMTP. The project also includes a separate IMAP proxy server written in C. Both components are released under the GNU General Public License version 2 or later.

Fetchmail is an open-source software utility for POSIX-compliant operating systems which is used to retrieve e-mail from a remote POP3, IMAP, or ODMR mail server to the user's local system. It was developed from the popclient program, written by Carl Harris.

Gnus (), or Gnus Network User Services, is a message reader which is part of GNU Emacs. It supports reading and composing both e-mail and news and can also act as an RSS reader, web processor, and directory browser for both local and remote filesystems.

GNUMail is a free and open-source, cross-platform e-mail client based on GNUstep or Cocoa. It is the official mail client of GNUstep and is also used in Étoilé. It was inspired by NeXTMail (NeXT's Mail.app), the predecessor of Apple Mail. GNUMail is based on the mail handling framework Pantomime. GNUMail demonstrated that it is possible to develop cross platform programs for GNUstep and Cocoa.

electronic mailing list manager

mailx is a Unix utility program for sending and receiving mail, also known as a Mail User Agent program. Being a console application with a command syntax similar to ed, it is the POSIX standardized variant of the Berkeley Mail utility.

Kolab is a free and open source groupware suite. It consists of the Kolab server and a wide variety of Kolab clients, including KDE PIM-Suite Kontact, Roundcube web frontend, Mozilla Thunderbird and Mozilla Lightning with SyncKolab extension and Microsoft Outlook with proprietary Kolab-Connector PlugIns.

FUDforum is a free and open-source Internet forum software, originally produced by Advanced Internet Designs Inc., that is now maintained by the user community. The name "FUDforum" is an abbreviation of Fast Uncompromising Discussion forum. It is comparable to other forum software. FUDforum is customizable and has a large feature set relative to other forum packages.

Zammad is a free helpdesk or issue tracking system. It offers the connection of various channels like email, chat, telephone, Twitter, or Facebook. Zammad is developed in the programming languages Ruby and JavaScript. The name Zammad comes from the Bavarian language and means "together".