> 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.