[Mimedefang] documentation bug/omission for newbies

[Joseph Brennan]

It's interesting to see Microsoft explaining MIME when their Outlook 
product does not parse it correctly. Now possibly the latest Outlook 
finally gets this right, but I know that as recently as 2 years ago it did 
not.

Given a message with this format:

message: multipart/...
part 1: text/plain
part 2: multipart/alternative
part 2.1: text/plain
part 2.2: text/html

Outlook ignored part 1 and displayed only part 2.2.

The situation above happened when a user's client was configured to compose 
only plain, and the user forwarded a message that was both plain and html. 
The new part, part 1, "hey look at this message I got", was not shown to 
Outlook users.

Relevance to MimeDefang is that action_accept_with_warning can result in 
the same structure. The warning is only text/plain.

Joseph Brennan
Columbia University I T