Roundcube - Free webmail for the masses. Roundcube webmail is a browser-based multilingual IMAP client with an application-like user interface. It provides full functionality you expect from an e-mail client, including MIME support, address book, folder manipulation, message searching and spell checking.

phpList is an open-source newsletter manager. phplist is free to download, install and use, and is easy to integrate with any website. phplist is downloaded more than 10000 times per month.

WebMail Lite Open-source webmail script for your existing IMAP server. WebMail Lite can be used to access mail on virtually any IMAP enabled mail server. The integrated web administration panel allows you to manage the system settings without manual editing config files.

SquirrelMail is a standards-based webmail package written in PHP. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 for maximum compatibility across browsers. SquirrelMail has all the functionality like email client, including strong MIME support, address books, and folder manipulation.

RainLoop webmail Simple, modern & fast web-based email client. RainLoop webmail was designed with efficient memory use in mind, so it can work fine even on low-end web servers. Regardless of mailbox size and number of mails in it, memory use per active user is always kept at a minimum, even when very large mails are processed.

OpenNewsletter is a web-based open source solution for sending email newsletters to a subscriber list. Email delivery options include an HTML version and/or a Text version.

Dada Mail is a Contemporary Mailing List Manager, enabling you to easily run a verified mailing list that your subscribers can trust, right on your own website. Dada Mail helps you with managing an email mailing list, offering complete support for safe, closed-loop opt-in subscriptions, sending out mass mailings, keeping message archives and allowing you to share your messages in lots of neat ways.

Postfix Admin is a web based interface used to manage mailboxes, virtual domains and aliases. It also features support for vacation/out-of-the-office messages.