AUC (Authenticated User Community) is an intranet system designed for use in an educational organization but is also useful in many other settings. It offers the ability for users to have a uniform web-based interface to discussion forums, e-mail (similar to hotmail, etc.), file management, and a searchable user database. Also, "Interactive Classrooms" provide a means for students and teachers to have a web-based extension to their in-class interaction. The system runs from a C-based monolithic CGI script. MySQL is used for database storage. Also, the web-based mail client supports MIME parts/attachments, IMAP, mbox, and multiple mail folders.
lfwmail is a lightweight webmail program. It will run with acceptable speed even on a Pentium 100Mhz Linux mailserver. It has just basic features and no calendar or folders, but it is fully MIME capable and can handle attachments. It is also very secure when you use https encryption. It converts HTML messages to ASCII for security reasons, but you can still see the HTML versions if you want. The code is clean and structured. The installation is straightforward and doesn't require a lot of non-standard modules.
Dolda Webmail (or d-mail for short) is a Webmail system written in PHP and interfacing with a back-end IMAP server. Advantages over most other projects of a similar sort are that it uses a persistant connection to the IMAP server (which increases performance on the Web server, reduces load on the network and on the IMAP server, and doesn't force the Web server to store the user's password in-core), and that it makes full use of XHTML 1.1 and CSS 2.
IGSuite is a Web-based groupware collaboration suite. It gives you a "box" of applications that includes wiki, email, documents, calendar, tasks, fax, contacts, notes, links, and more. The power of collaboration comes in when these individual suite components are shared and used within a group. It strives to provide location independence, platform independence, machine independence, and browser independence.
Mac Mass Mailer is a fully-featured mass mailer that supports message templates and a recipient database. It offers everything you need to create and maintain mailing lists for different needs and send mass messages directly from your computer at a very high speed. It uses Apple Mail's message delivery framework to deliver your messages. The recipient database is fully customizable. You can add as many recipient fields as you want and use them in message templates for the purpose of personalizing your messages.
The AmavisNewSQL SquirrelMail plugin gives you per-user control of a subset of SpamAssassin settings which are stored in a database. It also allows you to use a quarantine database for questionable mail. This plugin was designed with enterprise use in mind, and differs from other plugins in that it works with amavis-new rather than SpamAssassin directly. Most of the code lives in an external class that you can reuse in your own admin tools. It even has support for SOAP calls to perform common tasks.
kmMail is a PHP-based mail program, based on the mail functionality of Keftamail and is being developed by current Kefta employees. It is meant to be a framework for putting a web-based mail program on your site, but is still robust enough to drop into your current site with little to no modification. The goals of kmMail are MIME compliance, speed, low overhead, and an enjoyable user interface.