Peeto I tried to install fairmail via aurora store but received a message saying file is corrupt.
My reference to Fairmail should not imply that there is anything wrong with K9 Mail. Both apps are good and can handle OpenKeychain or PGP keys. Changing the MUA is a lot of configuration, especially if you have multiple mail accounts.
Is where I need some kind of Google application installed?
I was hoping to avoid all things google, that's why I'm surprised my photos go to google.
I have never used Opensource apps from the PlayStore and have never used Aurora Store, so I can only guess.
This may be because of the in App paid version for Pro features.
FairEmail FAQ
A little warning if you get the app from Github. Marcel throws out updates almost every day, sometimes several times a day. I sometimes wonder when he sleeps ;-)