I would like to perform the following task: converting a TRichEdit content (an rtf text) into a not-plain-text e-mail message body.
MAPI doesn\'t support rtf, but is
Apparently (googled this myself, as I mail some from Delphi, but not in this case), the PR_RTF_COMPRESSED option of (extended) MAPI may help you here. Also look at this.