Tuta is always encrypted I don't know where you got the impression that it was optional or that they could somehow magically make it work over IMAP without a bridge like proton.
> Tuta does not support the use of third-party email clients or the protocols IMAP/POP3/SMTP as we cannot guarantee end-to-end encryption of your data.
So it "breaks end to end encryption" even with smtps and imaps apparently. The few emails I received weren't from tutamail users so presumably came over SMTP.
It's confusing to know what they mean because they confuse terms. They say emails are "stored end to end encrypted".
