> evolution can connect to exchange, and iirc, includes a tray icon by
> default..

Evolution does indeed connect to Office365 using the docs at https://wiki.gnome.org/Apps/Evolution/EWS/OAuth2

Unfortunately it doesn’t have a tray indicator, and the evolution-indicator package never made it into Debian.

I will still give it a go for a while to see how it compares to thunderbird.