Always HTML 1 Requires Restart
by Arivald
Disable automatic degradation of HMTL mails to plain-text mails.
About this Add-on
https://bugzilla.mozilla.org/show_bug.cgi?id=414299 : Format | Auto-Detect: Messages composed as HTML with <tt> for "fixed width" sections or with simple links get sent as plain text
https://getsatisfaction.com/mozilla_messaging/tags/bug_414299
Note: if You use my other extension, Stationery, You do not need to install this. Stationery already contain this bug-fix.