[bawolff]

> In this scenario there isn't really the "known from elsewhere" info— knowing that certain groups of messages are returned together in response to sets of queries is unlikely to be meaningful if you don't have anything else to map that info to.

If the service knows the upload date of the message (presumably same as send date), and does this for a lot of users to cross correlate, that's actually quite a bit to go on to figure out who you are talking to.