[hs86]

I think they do: https://www.rfc-editor.org/rfc/rfc8621.html

However, there is little movement in the desktop email app space anymore, so aside from their web app, I see no other clients supporting this.

[ho_schi]

Thanks. That’s good!

Evolution added some nifty features lately (Markdown integration). And allows to use Client-Side-Decoration annd classic menus - usability wise awesome. Thunderbird got this year a complete redesign.

The other part are we as users.