You mean you currently do this but plan not to in the future

This step is what I was expecting you to talk about, and it has some tricky subtleties to get right, which is why I looked for it in the whitepaper.

A trivial problem with a naive implementation is being able to perform presence proofs using side channel information: send someone mail containing a terms you want to verify, and watch for the associated high level costs affecting operations that are likely to be incremental index change uploads.