HTML mail kind of works OK now, but we could probably improve it significantly by changing how some of the text mail sections render in their HTML version. For example:

• Email preferences could move to a new footer element.
• To/Cc can go in a footer element too? Or at least get like really small.
• Same with "Reply Handler Actions".
• Stuff like "TASK DETAIL http://blahblah/" could maybe become a "View Task" button?

So maybe we end up roughly like:

+--------------------------------------------+
| alincoln raised priority.    [ VIEW TASK ] |
| alincoln added a comment.                  |
+--------------------------------------------+

Four score and seven years ago...

+--------------------------------------------+
| Email Preferences * Footer Stuff Here      |
+--------------------------------------------+

Obviously this isn't very developed. Not sure if we can pull it off on mobile, either. From a technical perspective:

• We have to use only inline CSS since GMail just deletes all style tags, etc.
• Ideally, no images either.
• We can't do JS-driven reactive CSS stuff so we have very limited tools to make the mail behave differently on mobile vs web.
• Generally, keeping things simple is probably for the best? But some of these elements can have way nicer renderings in HTML than plaintext.