Addresses

We just got my son's first letter and on the return envelope is a different address than the one in the form letter. My son told us that "someone" said to use this new address. I wanted to be sure, so I called the Public Affairs Office of the Recruit Training Center but all I get is an answering machine or disconnected. I've also e-mailed but haven't heard anything. Does anyone work over there?? On the website, the address listed for my son's ship and division is the same as the one on the form letter. Which address should I use???