Kerio MailServer 5 is an e-mail server designed primarily for small and medium-sized businesses. Its critical components ? embedded McAfee Anti-Virus, integrated SpamAssassin anti-spam technology, and a full set of encrypted mail protocols including WAP for mobile phones ? deliver secure messaging for corporate e-mail users. For workgroups and larger corporations, Kerio MailServer features centrally managed address books, shared mailboxes, and mailing lists. Optional Kerio Fax Plug-in allows sending and receiving of faxes through e-mail. Users can be defined internally or managed through Microsoft Active Directory or Apple Open Directory. KMS runs on Windows, Mac OS X, and Linux Red Hat.