It's a simple question, but from what I've seen there aren't many reliable alternatives to Thunderbird. I want it to use ProtonMail. I found one called The Bat, but honestly, it's terribly ugly XD and I don't know if it's compatible with ProtonMail. I have also looked at applications like Rambox and Station, but the one doesn't seem reliable and the other is privacy friendly but hasn't been updated for a year.
Any ideas?
