@ricci Terrific about Thunderbird, thanks so much for the reply & advice.
I have the gmail app on Android & can’t see any way to log out of it - maybe I should delete the app? but have the impression that Google can get so much data from Android phones anyway that it may not make much difference? & degoogling an Android sounds challenging?
Some banks in Singapore have adopted compulsory phone-based security which won’t work if you have a single app on the phone not sourced from PlayStore :(