1 . Kite
Kite is an opensource replacement to Gmail. Kite is a webmail designed to look a lot like gmail and to be easily deployable on a single server. It’s written in Javascript with Angularjs for the frontend, and in Python 2 for the backend. It is released under BSD-license. Kite is still very much alpha software : it can only display individual messages. He hopes to get something a lot more useable in the next few months, though. He’ll start with threading, gmail-style, and the old school compose. Please feel free to fork it on GitHub and modify it as you like.
2. RainLoop
RainLoop is a Free, modern & fast web-based email client. With modest system requirements, decent performance, simple installation and upgrade, no database required – all these make RainLoop Webmail a perfect choice for your email solution.
3. MailPile
Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features. 100% Free and Open Source software. It’s free-as-in-freedom personal e-mail searching and indexing tool, largely inspired by Google’s popular proprietary-but-gratis e-mail service. It wants to eventually become a fast and flexible back-end for awesome personal mail clients, including webmail.
4. AtMail
AtMail 6 has been completely rebuilt from the ground up using Zend, jQuery, a true Web2.0 interface, Gmail email threading, inline attachment thumbnails, full IMAP/S support, CalDAV client/server – The aim is to provide users an alternative to Gmail or Exchange running on your own networks. It’s faster, lighter and more logical. The new version of AtMail really impressed me. It is very powerful and easy to use. The new user interface is absolutely stunning.
5. Litmus Scope
Litmus Scope helps you create a clean, web-based version of any email, with desktop and mobile previews. It’s perfect for sharing, and it’s totally free. Beautifully display the desktop view alongside an actual mobile screenshot. You can also peek behind the curtain and see how they pulled off that cool video or fancy text. Scope’s sleek code inspector makes viewing email source code a breeze. They even decode and clean up the HTML, making it crystal clear.
6. Roundcube
Roundcube is an open source webmail application with a slick, desktop-like interface. It is multilingual (already comes with 60+ languages) and offers most of the functionality you can expect from a webmail. Messages can be managed with drag’n drops, users can have multiple sender identities and it can work with unlimited users/messages.
7. Xeams
Xeams is a free e-mail server software that supports POP3, SMTP, IMAP & works in all major operating systems (Windows, Linux, Solaris, MacOSX). It comes with a powerful spam engine which can stop most of them by default & lets you to customize the rules further. The server is controlled from a web-based interface which also helps you to live-monitor the system.
8. After Logic
AfterLogic is fast and easy-to-use webmail script for POP3/IMAP mail server or cPanel.It offers mail server, ajax webmail with calendar, mail components, personal user settings, rich text editor, spell checker, mail filters and search, development and installation services.
9. T-dah
T-dah is a free PHP webmail application which is built from the well-known Uebimiau script & offers a slick interface. It can be up & running in a few minutes on any PHP (4 or 5) enabled server as no database is required. The application uses the POP3 protocol & can be configured to use SMTP, PHP mail, Sendmail or Qmail for sending e-mails.
10. SquirrelMail
SquirrelMail is an Open Source software written in PHP4 which provides both a web-based email application and an IMAP proxy server.
11. Xuheki
Xuheki is a fast IMAP client which aims to become your preferred email client. It works in your browser and you can access it from anywhere to read your email. It has most features that you would expect from a fine “Mail User Agent”.
12. Conjoon
conjoon is a web-based open source application, built with the Zend Framework, that focuses on message exchanging. Currently, it is a full-featured webmail & RSS reader client with contacts management. But the upcoming releases show that it will also have an integrated Twitter client with multiple accounts support. Thanks to Ext JS, the application has a slick desktop-like interface with tabs, drag’n drops & more.
13. Hastymail2
Hastymail2 is a full featured IMAP/SMTP client written in PHP. Our goal is to create a fast, secure, compliant web mail client that has great usability. Hastymail2 is much more lightweight than most popular web based mail applications but still maintains a competitive feature set. The project originated as Hastymail in 2002, then was nearly completely rewritten as Hastymail2 starting in January of 2008. We have had several stable releases of the second generation of Hastymail and development continues to be active.