Thunderbird

Website
F-Droid- Mobile version

Probably the most unappreciated app in existence. Powerful, Open Source email app recommended by many Privacy Tools. I use it on desktop computers, mobile devices, and portable gaming devices. It's like GMail or Outlook, which has its benefits and setbacks. Each client is its own client-side application. So email servers like Migadu don't sync read emails, presets, options, or anything like that between clients.

There probably is a way to sync across devices, I haven't cared. I've gotten my email to about where I want it, and Thunderbird supports what I need my email to do. There are a lot of features I have not fully utilized yet, like RSS. Thunderbird Mobile is a re-wrapped K9 Mail, which I used to use, but have now switched fully to Thunderbird because they are literally the same thing, different colors.