I keep two email applications – Evolution and Thunderbird. I use GNOME so Evolution comes as default email application. I want to use it but in practice this software is just too slow and simply freezes / crashes when Internet connection is off even temporarily. When it does freeze it’s not easy to close or shut down. There’s just so many user issues with it. So I install Thunderbird. It comes with all the features that equal Evolution and it’s fast. Fast enough. Plus it integrates encryption and signing with gpg.