I recently submitted a change of address request and was wondering if the USPS will send a confirmation letter to the old address (I do recall that they do send a "welcome kit" to the new address). And also granted the fact that they do send confirmation to the old address, can people still living at the old address do something that could prevent my mail from being forwarded to the new address, like can they send something back to the post office that this request was a mistake?