Both of those are usable but that’s about it. I use Evolution because it integrates with online accounts service well and I don’t have to mine for contacts, but overall it’s a sorry state of email clients in Linux world. Geary had nice ideas for a while, but it’s also dreadfully optimized and development has kind of stopped.

It’s also not such an easy to problem to solve either. Whole Gnome ecosystem got a lot better with new and modern applications with sleek designs, but email clients remain a pain in the ass.