If only one party uses those services one would have to trust Tuta/Proton to not save a copy of an incoming unencrypted mail. If a government wants access, they have to obey or shut down. Asking the unencrypted email provider from the other party is the obvious other way to access your data.
Only open source E2E for both parties is is trustworthy
For people recommending Tuta or Proton.
If only one party uses those services one would have to trust Tuta/Proton to not save a copy of an incoming unencrypted mail. If a government wants access, they have to obey or shut down. Asking the unencrypted email provider from the other party is the obvious other way to access your data.
Only open source E2E for both parties is is trustworthy