Enriched text
Enriched text was an unofficial formatted text format for email, defined by the IETF in RFC 1896 and associated with the text/enriched MIME type which is defined in RFC 1563. It never saw widespread use and was never intended to: This document is only a minor revision to the text/enriched MIME type that was first described in [RFC-1523] and [RFC-1563], and is only intended to be used in the short term until other MIME types for text formatting in Internet mail are developed and deployed.