Rainloop

RainLoop is a web based email client.

Afterlogic Webmail

Webmail is an open-source webmail script for existing IMAP servers.

There’s big news attached.

multi-channel inbox service for collaborative teams

Gmail is available across all your devices Android, iOS, and desktop devices. Sort, collaborate or call a friend without leaving your inbox.

Horde Groupware is a free, enterprise ready, browser based collaboration suite.

MDaemon Secure Email Server for Windows - MS Exchange alternative; POP3, SMTP, IMAP email server featuring web mail with spam protection.

Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features.

Mailspring is a mail client for Mac, Windows and Linux.

Secure Email Gateway

Starting with version 0.9.8, mu provides an emacs-based e-mail client which uses mu as its back-end: mu4e.

Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.

The Power Email App for busy professionals, like you.

Web- and IMAP-based email service. 2GB cost 1€/month.

Secure email with absolutely no compromises. Get your free encrypted email account today.

Web-based IMAP email client

SOGo is groupware server with a focus on scalability and open standards.

SquirrelMail is a standards-based webmail package written in PHP.

Get your encrypted mailbox for free.

Open Source WebMail Lite is a free community edition of full-featured WebMail Pro server applicatio…

Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more.

Zoho Mail is a webmail service built with the needs of a modern business in mind.

A fully fledged, free email server solution, an open source project (GPL v2).