Gnome's Evolution is quite good as well and the built-in exchange support for both email and calendar via EWS works better than the thunderbird plugin. I used t

Gnome's Evolution is quite good as well and the built-in exchange support for both email and calendar via EWS works better than the thunderbird plugin. I used to use thunderbird, but after several troubles with the exchange plugin (e.g. meetings on Fridays disappearing) and calendar not working properly I switched to Evolution where it just works.