Open Source ChromeOS 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.

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

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.

Trojitá, a Qt IMAP e-mail client

Proton Web Clients is a monorepo hosting the web applications for Proton’s suite of privacy-focused services, including the core Proton Mail webmail interface and related web apps like Proton Calendar, Proton Drive, Proton Account, Proton VPN, Proton Pass, and other connected tools. It consolidates all web client code, shared modules, dependencies, and development tooling into a single repository, enabling unified maintenance, consistency of design patterns, and efficient evolution of Proton’s online interfaces. These web clients run entirely in the browser, letting users securely interact with their email, calendars, files, and other services without needing native software installed, and benefiting from end-to-end encryption where applicable. The monorepo includes application logic, UI components, build scripts, and testing infrastructure for reliable deployments and streamlined continuous integration.

Mailcrypt is an Emacs Lisp package which provides a simple interface to public key cryptography with PGP [and now GnuPG!]. Mailcrypt makes strong cryptography a fully integrated part of your normal mail and news handling environment

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

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

MultiMail is an offline mail packet reader for Unix and other systems. It currently supports the Blue Wave, QWK, OMEN, OPX and SOUP formats. It has a full screen, color user interface, built with the curses library.

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.

The continuation of the Alpine email client from University of Washington.

PHP app to access Gmail/Googlemail/Gmail-for-Your-Domain accounts on wireless devices. Convenient alternative access method to your email account on the move, gmail-mobile incorporates as many Gmail features as possible within limits of a mobile device.

Web based e-mail reader

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.

OlivaMail is a set of the java e-mail solutions: Webmail, Java Email Client (GUI), Command Line Utility (CLI) and the Core library.

MH-E is the Emacs interface to the MH mail system. It offers all the functionality of MH, the visual orientation and simplicity of use of a GUI, and full integration with Emacs, including thorough configuration and online help. Since MH-E 8.6 was released in 2016, its development migrated to the Emacs repository. Thus, if you install an Emacs package, or check out and compile the Emacs source, then you will be running the latest version of MH-E. Consequently, we will retire this site once all of the tickets are resolved. Therefore, please help us out and submit new tickets with M-x report-emacs-bug. MH-E is now only supported in the version of GNU Emacs in which it appears. It is no longer supported in XEmacs. It is compatible with MH versions 6.8.4 and higher, all versions of nmh, and GNU mailutils 1.0 and higher.

Eridu is a web based groupware package written in PHP that aims to provide all the functionality expected of a professional groupware package such as MS Outlook+Exchange or Lotus Notes+Domino.

Spamato is a spam filter system that combines several anti-spam techniques, from which thousands of users benefit. It is available as an add-on for Thunderbird and Outlook, and as a stand-alone proxy for other email clients. IMAP and POP are supported.

BitMail is a Proof-of-Concept- / Design-Study for an Qt E-Mail Client. POP3 / IMAP / SMTP / P2P E-Mail-Client. ● Qt E-Mail Client. ● Build-in Encryption to secure E-Mails ● IMAP & POP3 ● Additionally a full decentral P2P Email-Option via the Echo Protocol ● Store Email for Offline-Friends in the P2P Network. ● Chat and Instant Messaging is build in. ● POPTASTIC function (Chat over Email) ● Calendar widget functionality. ● Open Source. BSD License. "Cassiopeia is the tortoise of Momo, which can communicate through writing on her shell and guides into the future." - Wikipedia. Source from: https://sf.net/projects/spot-on/files/ & https://github.com/textbrowser/spot-on

JMail is a mail client written in Java. It handles attached files, HTML mails, filters and other stuff... It can be used with a LDAP directory.

WebMail is a Java Servlet application that gives users WWW access to their IMAP/POP mailboxes. It supports folders, multiple languages, composing messages, MIME and virtual domains.

Phosta is yet another web-mail system, written in PHP, that wants to be fast, lightweight, simple to configure and fully customizable in about all of it's parts.

popper_mod-wid is a free, full featured web based email client written in PHP. It is an extension of the now abandoned "popper_mod" project which was an extension of the origional popper. It runs on any server that can run PHP and mySQL. Uses POP and S

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.

6XMailer is a PHP POP3 mail reader with support for HTML mail, MIME attachments, embedded mail content, multilingual ready, and themes. It has an address book and centralized configuration file.