Replex is an administrative tool for managing email on any Unix-like OS. It can handle multiple domains, users, mailing lists, etc. without requiring creation of Unix user accounts for mailboxes or authentication. Replex is written in PHP4 and stores all information in a MySQL database. Replex relies on Postfix for SMTP and Cyrus for IMAP and POP3 accounts.
Ristretto is the mail API that is used by Columba, a Java mail client (http://columba.sf.net). It is available as a stand-alone API, and it provides a well-tested, slim, and fast Java implementation of all relevant mail protocols and features. It is licensed under a MPL/LGPL/GPL tri-license.
Rumble is a mail server suite for SMTP (ESMTPSA), HTTP, POP3, and IMAP4v1 with an extensive C/C++ and Lua API for scripting. It comes with support for SSL/TLS, SQLite, and MySQL and has a Web-based administration and Web mail feature. Additional included modules feature greylisting, DNS blacklisting, SpamAssassin support, and dynamic performance scaling as well as a multithreaded structure that allows for clustering of multiple servers for one or all domains. With the Lua API you can create your own new server mailing lists, CRM software, e-marketing, and other extensions within minutes.
SSA Fetchmail is a multi-threaded solution that retrieves new emails from ISP email accounts and forwards them through different channels like email, SMS, or a local SQL repository. It supports IMAP4, POP3, SSL, SMTP TLS delivery, SMPP SMS delivery, and local delivery. SSA Fetchmail supports thousands of email accounts provisioned in a MySQL database. Its performance is better than other solutions.
Scalix Community Edition is an email and calendaring platform. It includes a full version of the Scalix industrial-strength server and AJAX-based Scalix Web Access (SWA), a cross-browser, cross-platform Web client. Community Edition also includes 25 free premium users that can use MS Outlook for email and group scheduling.
Scalix Virtual Appliance includes a full installation of the popular email collaboration software Scalix. The only two applications installed in addition to Scalix and its required components are Joe (a simple text editor) and VMware Tools. This appliance should work with any recent version of VMware.