return service requested playskool2005-03-31 03:43:16

I just received the document from INS for the authorization for parole of an alian into the Unites states. My question is: why is there a stamp of "return service requested" on the envolope?
What does it mean by "return service requested"?

Thanks a loooooooooot.

就是告诉邮局，如果此人不在此地址，请将信件退回

拜谢 叩首