It would work in the same way as opening any encrypted mailbox works. Your password is used as the key to decrypt your mailbox when you login. The same key coul

It would work in the same way as opening any encrypted mailbox works. Your password is used as the key to decrypt your mailbox when you login. The same key could also be used to search the email. Right now they're already telling you that they scan every email. So yeah, you would have to trust them that they do in-fact discard they keys and don't allow decryption in other scenarios. But large companies with tons of cash to lose if they're sued, will rarely blatantly lie about what they're doing.