Courier mail server - Fax<->mail gateway

 The Courier mail transfer agent (MTA) is an integrated mail/groupware
 server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP,
 TLS, and HTTP. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list
 services within a single, consistent, framework.
 .
 The courierfax module implements a faxmail gateway, which faxes a printed
 copy of an email message to the phone number specified in the email address
 (e.g. 5558888@fax).