Hello andrewclark55,
Thank you, and I’m glad you enjoy Aqua Mail on Android.
At the moment, Aqua Mail does not have a native Linux version. A direct port from Android is unfortunately not simple, because Aqua Mail depends heavily on Android services, storage, notifications, background sync, account handling, and mobile UI components.
For Linux with IONOS Exchange, the best practical options are Thunderbird with Exchange/IMAP support, Evolution with EWS if supported, or IONOS webmail/OWA.
I’ll pass your request as feedback. A Linux version would be interesting, but I can’t confirm any current plan or timeline for it.