AfterLogic WebMail Pro is a browser-based e-mail and collaboration front end, designed to work with your existing messaging solutions. From an administrator's perspective, the application is easy to install on your own server, easy to integrate and easy to maintain.

Works with your e-mail server
Linux: Exim, Postfix, Courier, Dovecot, Sendmail, Qmail and many others.
Windows: Microsoft Exchange, Windows POP3 Service, MailEnable, IceWarp, MDaemon, hMailServer, and many others.

Fits Hosting and Telecom requirements
WebMail Pro system architecture is compatible with high availability cluster implementations. The software is optimized to work under heavy loads and to support large numbers of mailboxes.

Works in a cluster! WebMail Pro can be used in cluster environments to maximize performance and system availability. Existing large cluster implementations scale to millions of users.

Natively supports cPanel, Plesk, and DirectAdmin.

It's easy to integrate WebMail Pro into cPanel (learn more).
It's also easy to integrate WebMail Pro into Plesk (how to).
Automated installer is available for DirectAdmin as well (learn more).