Mailspring is a pretty decent email client (and actively developed)

https://preview.redd.it/yissw00vio1h1.png?width=2944&format=png&auto=webp&s=e197a41b5699ce32666e89abcea24c2ecbf66379

After periods of using Thunderbird, and then Geary, I was getting annoyed with their various shortcomings.

At a minimum I need a one line preview of each email in the message list (which isn't even on the Thunderbird roadmap). Also Thunderbird is memory heavy and still feels clunky despite the partial UI makeover. Geary is fine, but uses old toolkits and is showing its age (also no longer developed). Sometimes html messages don't render correctly in Geary (I believe it uses webkit).

Mailspring went through a period of hardly being developed. But I think the main Dev switched to Linux last year, and now there's very frequent updates (https://www.getmailspring.com/changelog). Also they abandoned needing an account to use it. Developer is responsive to bug reports on Discourse.

Default theme is ok but dated. Switching to the inbuilt Darkside Theme (created by a graphic designer), and it looks great and modern.

https://github.com/Foundry376/Mailspring

https://redd.it/1tfmgu5
@r_linux