AfterLogic XMail Server is a free open source e-mail server for Windows and Linux platforms. Includes AJAX-enabled webmail and web administration module, supports ESMTP, TLS/SSL secure connections, SMTP authentication, account and domain aliasing, anti-spam features (IP-based and e-mail address based),mailing lists, logging, remote administration, Finger protocol, filters, custom mail processing, simultaneous multi-user access to a POP3 mailbox.