Is that an April fools joke? Proper encryption suites don't produce something that looks like a Caesar cipher, it's just a solid block of seemingly random data. You can't really index something like the words inside an email unless you first decrypt it.
Right, I do understand that with some setup involved, there are ways to search against encrypted messages but simply being given a brand new chunk of encrypted data with no prior knowledge of the contents would be impossible for anyone to index other than the recipient using the key. There would definitely be a way for the client-side to automatically download an encrypted email, decrypt it, index it, and keep an index database using whatever method while simultaneously keeping the originally encrypted email secure on the server.
