IMAP Gateway: Outlook requires alternative text/plain to display text/html

Outlook over Mapi

current process:
if an email is appended via IMAP Gateway, and if the email contains only a text/html part without an alternative text/plain, then Outlook will not show the mail.

Fix required in CmdAppend/Mime2Mapi.
-- email in that case needs to be stored with an text body.

Fix required in CmdFetch/Mapi2Mime ??
-- needs to register, if an email has arrived with an text/html part only. Fetch needs to reproduce the email with an text/html only as well