No action, but note/discussion:  I think it might be better to hand this off of extraFlags for consistency with IMAP.  It's a little awkward because IMAP supports an array here but ActiveSync has't needed it yet.  But in the future I think we will want an array so we can explicitly test and call out that we issue multiple requests when the server is giving us limited batches.  (We would probably just configure the test server down to like 5 messages per batch instead of using a large number, of course.)

Since filterType already does this, I think it makes sense to leave it like this for now and refactor it in the future, though.