Kerio MailServer 5 is an email server designed primarily for small and medium-sized businesses. Its critical components - optionally 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 email users. For workgroups and larger corporations, Kerio MailServer features centrally managed address books, shared mailboxes, and mailing lists. Users can be defined internally or managed through Microsoft Active Directory or Apple Open Directory. Available with Kerio Fax Plug-in, which allows sending and receiving of faxes through email. KMS runs on Mac OS X, Windows, and Linux Red Hat.