This will setup the Raspberry Pi to act as a mail server that will take any emails sent to mail2fax@myfaxserver.example.com and will send out a fax from that received email. The PI  makes a great, low-power-draw server with a USB modem. A modem that works well is the U.S. Robotics USR5637 56K USB Controller Dial-Up External Fax Modem with Voice

Notes on setting it up for postfix and mail-to-fax capabilities

* Get and boot with Raspian

* Find out what com port is assigned to the modem