The best FOSS mail apps I came across, are 1.) Evolution (Gnome / Linux) Although it may not be the shiniest star, it has a huge feature set and works pretty

The best FOSS mail apps I came across, are 1.) Evolution (Gnome / Linux) Although it may not be the shiniest star, it has a huge feature set and works pretty good for me. 2.) Mailspring It is a pretty good Mail.app Alternative, but I did not like the restrictions and the user interface was pretty unpolished, although pretty Mail.app-like The most annoying part on all Mail apps I tested was the search. It was mostly unusable, if you have ever used macOS Mail. The search is so much ahead of every other mail app I tested (and I tested a ton) that I don't know if it is just hard to build it or no one ever tried to rebuild the Mail.app search. The only app that was pretty close was mutt/neomutt, but although I like terminal interfaces, in Mail I often use Mime features like bullet lists, tables, Image previews and other stuff that is hard to do in Terminal UIs.