I saw the popularity on AUR several times and installed but couldn't figure out why people use it.

Their website cites GDPR or whatever and is honestly kindof meh.

I was interested in the conversation layout, advanced email headers and recoloring things like folders but idk if they have that or not.

Also I've always been annoyed that half the dialogs are integrated tabs and the compose email is a window that can't be nested. I can't remember if they fixed that or not.

I wasn't personally impressed by the logo, it reminded me of a 2000s Mozilla but maybe that was intended. It didn't have enough distinguishment from other Mozilla products while communicating that it was for Email or related to Thunderbird. It honestly looks like a browser.

/opinion