XFMail is an X11 application for receiving electronic mail. It implements most of its email functionality internally so that it does not depend on a lot of extra packages. It supports POP3, MBOX, IMAP4, sendmail, and SMTP. It has built-in support for interfacing with PGP, GPG, ispell/aspell, faces, LDAP, and esound. It runs on most Unix variants.
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.
Webtop is a Web-based POP3 email client that includes SSL encryption, Mozilla support, many email filter options, spam fighting features, custom folders, email import/export, fast searching, undeliverable email bounce, intelligent read receipts, and email-to-PDF generation. The Webtop also includes a calendar, notepad, online file storage, automated email reminders, contacts, mailing lists, and Web-based administration. One installation can support multiple users and each user can set up as many POP3 accounts as they need.
Liferay is an enterprise portal. It handles users and portlet drawing, has a full administrative interface, supports all the major databases and the main J2EE application servers, and has single sign-on capabilities and multiple language support. It uses Apache Lucene for document searching. A number of portlets are included, including a guestbook, a calendar, a mapping utility which uses Expedia, news, polls, a document library, and live stock information.
The Gordano Messaging Suite (GMS) is a highly flexible and reliable suite of messaging products. Customers can choose which components meet their needs from email, Webmail, collaboration, instant messaging, calendaring, SMS, and list server software all of which can be complimented by high level anti-spam, anti-virus, and archiving options.