Open Source Email Clients

Strike the 'T' key to sort messages by thread, strike the 'U' key to sort unthreaded again, just like the 'G' key switches to Grouped By Sort view.

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

Mail Notifier is free, modern email notifier with the latest user interface trends for Windows 10/11. It supports multiple accounts and IMAP/POP3 protocols. Enjoy customizable notifications, message previews, and more, all in 18 languages! For more details, please refer to the readme.txt file (Files tab, description below). Note: Gmail support is currently unavailable due to verification requirements by Google.

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.

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

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.

Roundcube Webmail is a browser-based, multilingual IMAP client with an application-like user interface. Roundcube provides the full functionality you'd expect from an email client, including MIME support, address book, folder manipulation, message searching, and spell check. Roundcube is written in PHP and JavaScript.

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.

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.

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

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

Note! Code and issues are maintained at https://github.com/sba1/simplemail. SimpleMail is a simple to use but powerful mail client. It supports the SMTP, POP3 and IMAP (in a simple form) protocols. Furthermore, among much other features, it is capable of showing HTML mails and can identify spam mails by using a Bayesian filter.

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.

phlyMail is a Webmail and data hosting application. It features IMAP, POP3, SMS, Fax support, a Calendar, Bookmarks, files manager. Multiuser and single user editions available.

Manitou-Mail is a free Qt-based database-driven Mail User Agent with associated scripts. It stores mailboxes and mail messages as structured data, accessible (possibly concurrently) by SQL, in addition to providing common mailer features and some more.

EGroupware has moved to Github, please find all our downloads there: https://github.com/EGroupware/egroupware/releases EGroupware is a multi-user, web-based groupware suite. Currently available modules include: email, addressbook, calendar, infolog (notes, to-do's, phone calls), content management, wiki, project management, tracker, timesheet, knowledge base, CalDAV/CardDAV

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.

The most complete Business Webmail with Mobile client application for companies of all sizes. All the core functions for business like calendaring and integrated webmail, plus the capability of converting emails into business objects such as: quotes, invoices, marketing stuff, customer requests, project management and more. A simple way to have a unique flow of information from email request from customers to invoices!
You only have to choose which modules you want to activate and is done!
Built with PHP, loves MySQL but runs also on SQL Server and Oracle.

LNMail is a graphical user interface to access your Lotus Notes mail messages. It is mainly intended to organize the messages stored on the Lotus Notes server. Since by default the space of your Lotus Notes mail account is limited, LNMail gives you easy and seamless access to your created archives. Organization and finding mails should now be easy.

a webbased desktop, which handles modules like email-app and so by a webclient. Today only for Mozilla like Browsers. Tester/Developer are welcome :) Check it out on http://x.nebulon.de/netdesk/

An os-independent Email Client written in Java. It's also runnable from usb-stick.

SimpleCheck is a fast, low resource, server oriented, Windows System Tray based E-Mail Notification Client with a simple UI that regularly checks multiple POP3 E-Mail accounts. Many full client features; immune to viruses; use to delete SPAM mail.

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.

Mozilla Thunderbird 2.0x under Mac OS X has the disadvantage that it can not use the integrated address book. This version can use the Mac OS X Adress Book with LDAP. The Patch for this is from Mozilla Bugzilla. IMPORTANT: READ THE RELEASE NOTES