Comment 4 for bug 66332

Updating summary per comment 3.

> However, with rare exception, I am asked how I want to send. There appears to
> be no rhyme or reason to the exceptions.

I don't know how you normally go about composing in HTML, but in a quick test I
got the HTML Mail Question only for messages with some sort of formatting --
even something simple and easily "translated" to text like bolding. For
messages without formatting, they're converted to plain regardless of the Send
Options settings.

Both cases' behavior is consistent with how mail is handled for recipients of
"unknown" preference.