> When the recipient is a Gmail user (enterprise or personal), Gmail sends an E2EE email. The email is automatically decrypted in the recipient's inbox, and the recipient can use Gmail in a familiar way.
So what happens with Search?
Random unpolished idea: a (local) search engine that runs when seeing the email and stores the keywords encrypted in its index..
So if you're looking for "Nigerian prince" it will look up "Avtrevna cevapr" and return references to the emails containing that term.
ProtonMail downloads the whole mailbox to browser storage to support fulltext search.