I completely agree. Having a more semantic structure rather than "anything goes" HTML can only be a good thing for the state of emailing in 2016. Many high pro

I completely agree. Having a more semantic structure rather than "anything goes" HTML can only be a good thing for the state of emailing in 2016. Many high profile websites don't even bother sending a text/plain alternative with their emails anymore and the HTML is often cryptic when viewed from a text browser. Anything that can improve this is a good thing. I do have a minor beef with this implementation however: at first I assumed that this metadata would be stored in custom email header (X-Mail-Action or whatever) but as far as I understand it's embedded in the HTML instead. It would make it more painful to add support for that to existing clients, especially if they use external tools to display HTML.