http://www.rfc-editor.org/rfc/rfc2532.txt
RFC 2532: Extended Facsimile Using Internet Mail, L. Masinter, D. Wing1999-03-01T23:00:00-00:00This document describes extensions to "Simple Mode of Facsimile Using Internet Mail", and describes additional features, including transmission of enhanced document characteristics (higher resolution, color) and confirmation of delivery and processing. [STANDARDS-TRACK]