Open Source Email Clients

SquirrelMail is a PHP-based Web email client. It includes built-in pure PHP support for IMAP and SMTP, and renders all pages in pure HTML 4.0 for maximum compatibility across browsers. It has strong MIME support and a flexible plugin system.

NOCC is a simple and fast Webmail client which can handle POP3 and IMAP mailboxes and sends email via SMTP. It is written with PHP, has low requirements (no database, frames). Features multi-language support, MIME attachments, displays HTML messages. The installation guide comes with the source code: https://sourceforge.net/p/nocc/code/HEAD/tree/trunk/webmail/docs/INSTALL If you encounter problems or bugs you can always try the current HEAD version: https://sourceforge.net/p/nocc/code/HEAD/tarball?path= Questions, bug reports or support requests are very welcome: https://sourceforge.net/p/nocc/_list/tickets Alternative source code repository: https://github.com/oheil/NOCC

This email notifier sits in your system tray and pops up a notification when new messages arrive. Preview your email before downloading it to your mail client or launching webmail applications. Create rules to delete or change the priority of messages. This program builds upon the open source PopTray mail notifier adding many new features including Windows Vista/7/8/10 support, UTF-8 and unicode support, HTML Preview, IMAP support, TLS & SASL support, etc.

SaltOS is a Business Management solution 100% Cloud Computing. It integrates features like CRM (Customer Relation Management) and ERP (Enterprise Resource Planning). Moreover is it licensed as 100% free software GPL-3.0.

IGSuite is a web-based Integrated Groupware Suite oriented to be a CRM solution. In the Suite you can find: IGWebMail, IGCalendar, IGContacts, IGArchive, IGWiki, IGTodo, IGChat, Projects, IGFax an HylaFax client, IGFileManager, IGMsg and many other.

Hastymail is a fast, secure, rfc-compliant, cross-platform IMAP/SMTP client application written in PHP providing a clean web interface for sending and reading E-mail. This version of Hastymail is no longer being developed. We are now working on a new version, Hastymail 3, AKA, "Cypht". http://cypht.org

GoldBug is a decentralized & secure communication suite that offers an integrated e-mail client, an instant messenger & a file transfer. Also included is an URL-RSS-DB & a p2p web search. Current vers. w/ McEliece Algorithm. GoldBug has been 2013 - 2023 ten years just another Graphical User Interface of the Spot-On Encryption Suite. Main GUI features: Minimal & colorful Interface with Tabs in the East. Microsoft & Qt MinGW deprecated Win32 & for Compiling: ● https://sourceforge.net/p/goldbug/wiki/compiling As Spot-On implemented the minimal GB-concept & Nuvola Icons, GoldBug has now been fully integrated into Spot-On Win64: Just choose Tabs at East & Mini-View in Options - w/ Nuvola Icons of course! Voilá! & Many Thanks, Pro-Files can be found archived at ● current source: https://github.com/textbrowser/spot-on ● EN Manual: https://www.amazon.com/dp/3749435065 ● DE: https://compendio.github.io/goldbug-manual-de/ ● Study: https://www.amazon.com/asin/dp/3750408971

AfterLogic WebMail Lite PHP is a free AJAX webmail application. Users can receive, view, manage, compose, and send email through web interface (IMAP and SMTP supported). Source code included.

Columba is an email client written in Java, featuring a user-friendly graphical interface with wizards and internalionalization support. Its a powerful mail management tool with features to enhance your productivity and communication.

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.

Modest system requirements, decent performance, simple installation and upgrade, no database required - all these make RainLoop Webmail a perfect choice for your email solution.

SquirrelOutlook is a standards-based webmail package written in PHP4 (Squirrelmail). It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 for maximum compatibility across browsers.

Webmail with support for MIME mail, address book, plugin system, differrent themes and languages. Runs on PHP, MySQL and connects to IMAP servers.

Special Folders Plugin is a plugin for the popular webmail Roundcube. This plugin lets the admin define new special folders, which will be displayed at top of folders lists. Admin can directly choose the real mail folder, a name for it and the icon.

Is an ASP.NET webmail application written in C#. It uses a POP3 or IMAP servers as the mailstore and sends mail through a SMTP server. You can compose HTML messages, search your inbox, read complex mime messages and much more. .NET and Mono compatible.

This is a Web Mail application written in C. This uses its own users/mailbox system and it allows remote users to create accounts from a WEB form. The accounts are not valid users on the Unix system. It works like a Hotmail or Yahoo service.

NOTICE: Keep in mind that POP3ye is alpha software and by definition it is a long way from finished. POP3ye is a fully featured web-based e-mail client written in Object Oriented PHP 5. It ony supports the POP3 protocol.

A modern variant of Phoenix Mail

This plugin adds to RoundCube the ability to easily give different permissions to users by creating a roles table and assigning users to it. This and other plugins may use its public function to register permissions and admin them with this plugin.

jwma (java webmail app) uses jakarta mail (formerly javamail) to provide access to an imap email store. Multiple users can authenticate, read, send and manipulate email storage and persist a list of contacts, email identities and their own individual preferences. It works with email stored in mbox or maildir format or stored in a derby database; it has been tested with dovecot.james and exim4. See http://jwma.sourceforge.net/ for further details.

The Mailredirect extension for Mozilla Thunderbird and Mozilla SeaMonkey adds the ability to redirect one or more email messages to one or more recipients. The feature of email redirecting is also known as remailing or resending. The extension is an answer for https://bugzil.la/12916

Free and easy-to-use webmail script with AJAX interface. Supports POP3/IMAP accounts, SMTP, SSL. Users can check and send mail, use address book. Skins, non-English languages, UTF-8. MS SQL/MySQL/MS Access backends supported.

"Archive This" is an add-on for the Thunderbird email client that provides shortcuts for filing messages into folders rapidly and efficiently.

AUC for Education is an GPLed intranet system designed for use in a K-12 setting that provides a web-based environment for students and teachers to interact via "Interactive Classrooms" and other innovative features.

BlogMail software is a CMS and a Webmail application integrated in one. It's based on WordPress MultiUser and has all the functionality of this, like RSS and comments, plus support for LDAP, smarty templates, automatic subdomains and antispam filtering.