AfterLogic WebMail Lite PHP

Free and easy-to-use PHP webmail script with modern AJAX interface. Supports POP3/IMAP accounts, SMTP, SSL (including Gmail). Users can check and send mail, use address book. Skins, 3-pane view, non-English languages (including right-to-left Arabic and Hebrew), UTF-8 and other charsets, IMAP folders, view and compose HTML mail. MS SQL/MySQL backends supported, multiple mail accounts and domains, web-based administration and installation, cPanel integration.

The license is AGPLv3. The product can be upgraded to Pro version with extended features and no AGPLv3 restrictions.