In our five years at the school, the only correspondence we ever received by mail was test results in late June. We're not planning to move before July 1 anyway. Oh, and one year that letter did come back to them as undeliverable (we had moved -- a different apartment in the same building -- and the change of address form I had sent to the school must not have gotten recorded.) It took several phone calls to get that fixed, but it really did not appear as if the idea of people deliberately hiding their change of address was even on their radar. I am not saying everyone should do it, or even that we will do it, but it does seem like the probability of "getting caught" is extremely low.