AfterLogic XMail Server is an email server. It supports ESMTP, TLS/SSL secure connections, SMTP authentication, account and domain aliasing, anti-spam features (IP-based and email address based), mailing lists, logging, remote administration, the Finger protocol, filters, and custom mail processing. AfterLogic XMail Server is based on the XMail server, but features simultaneous multi-user access to a POP3 mailbox, the ability to configure port numbers via a configuration file, a Windows installer, and a Web administration tool with an AJAX interface.
AldoContent is a lightweight CMS focused on usability and simplicity. It is designed for multilingual Web sites and can have sections with public and private content. It has file management, is extensible with plugins, and uses gettext for localization. Is written in PHP for a MySQL backend.
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.