[MlMt] Do we need a better way to disable text/not-really-plain?

[Bill Cole]

For a fan of standards and simple email, the last token in this MIME 
sub-part header generated by MailMate is appalling:

   Content-Type: text/plain; charset=utf-8; format=flowed; 
markup=markdown

Even worse: that non-standard "markup=markdown" parameter causes 
MailMate to translate what is labeled as "text/plain" into HTML which it 
then renders, instead of simply presenting the plain text. This can 
include turning supposedly-plain text incantations into active 
(clickable) strings and hiding the original text. WHICH IS AS WRONG AS A 
TEXT/PLAIN RENDERER CAN GET! Nothing in the Preferences dialog can 
disable this. None of the documented "hidden" preferences set via the 
"defaults" command touch it.

It is true that I have grumbled about this before and that Benny offered 
a workaround: 
https://www.mail-archive.com/mailmate@lists.freron.com/msg00673.html. 
Unfortunately, that's really only fit for paranoid Luddite mail Puritans 
like myself who are comfortable with how that switch operates.

Is the audience for a better default behavior and/or a more 
support-worthy switch larger than myself and the small crowd of very 
geeky people I've convinced to use MM? Put another way: is no one who 
doesn't work professionally with the problem of email as an attack 
vector even bothering to disable this misfeature?