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.

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.

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

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.

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.

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.

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

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.

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.

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.

Notifier for multiple Gmail and Google Apps email accounts. Offers various notification options (unread mails in Inbox only, All Mails, or with specified labels) and alert methods (popup message, chime, blink keyboard LED). Uses IMAP over SSL.

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.

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

Mobile Mail Checker is a mail client for portable devices: java phones/smartphones/PDAs. It is based on J2ME. The most important features are: POP3/IMAP/SMTP support, reading/writing/replying/forwarding mails, SSL support, multimedia attachments supported

Browsing your mail on mail server, And deleting mails without downloading.

The Secure Electronic Mail System will be a system for sending, receiving, and transporting over the internet of messages and documents in a manner that is secure, with complete and accurate identification of senders, receivers, and transport agents.

An ldap based addressbook application. Ldap-abook is intended for users wishing to maintain a centralized addressbook which is accessible by multiple users, computers, and email clients.

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.

Webmail client for call center agents. Designed to efficiently manage and report on a large number of emails to a small number of email addresses. Specifically designed with webforms in mind where one email address may receive over 1000 emails per day.

A GUI-based email application capable of recording, compressing and sending voice messages.

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

Attachment Reminder is an Add-On (extension) for Mozilla Thunderbird that scans outgoing email for user-defined keywords (or just use the default list), and prompts you if it looks like you wanted to attach a file but didn't.

BasiliX is a webmail application based on PHP and IMAP, and powered by the MySQL database server. It supports simple mail actions, sending/receiving attachments, an addressbook with group capability, configurable, multiple languages and multiple folders