I've been using Tutanota for years, but now I'm looking to migrate due to the missing IMAP/POP3 Bridge, inability to easily export all emails and slow search performance - Old emails essentially become irretrievable.
We also plan to re-build the search, as results on the browser are not good enough. In our apps (desktop & mobile) it works much better, please try search there!
Unfortunately, we can't build a bridge as this would leave your emails decrypted in a third-party client and open to tracking and vulnerabilities there. We can't allow that and promise maximum security at the same time... In the Tuta clients all your data is always encrypted.