If you need to cancel your change of address request or modify anything like mail forwarding start date, end date, type of move, email address, phone number, etc. you can do this online or in-person. In both cases, you’ll need your confirmation code. The confirmation code is a 16-digit code that is sent to your email address if you’ve applied for a change of address online or sent to you by mail at your new address. If you’ve lost your confirmation code, you’ll have to go to your local Post Office to update or change anything.