Qustion isn't exactly clear. Do you mean you sent him something via certified mail with a return receipt requested and he kept the return receipt without returning it? If it was sent to him, I do not believe that even the FBI has that power, it is a violation of US postal Service Regulations. If he kept it as a method of obtaining the address of the person who mailed it to him, he should have copied it and then returned it. If this doesn't address your question please try to word it more clearly.
To the Sender
FBI
Return to sender does not require quotation marks or a comma.
We can't know the answer to your question.
The cast of Return to Sender - 2005 includes: Stephen Danby
The cast of Return to Sender - 1999 includes: Brett Baker as Peterson
Return to Sender - 2006 II is rated/received certificates of: UK:U
Return to Sender - 2011 III was released on: USA: 22 September 2011
They take it to the post office and leave a notice that they will try again or you can go to the post office to pick it up. There will be a deadline. If you miss the deadline, they will return it to the sender.
Contact the sender to see if they have a copy.
The cast of Return to Sender - 2013 includes: Sian Buckland Dan Eycott as Postman
One of two things can happen, 1. Return to sender 2. Delivered Postage Due. return to sender?