help

just the same day got two email from USCIS
1.
Application Type: I485 , APPLICATION TO REGISTER PERMANENT RESIDENCE OR TO ADJUST STATUS

Current Status: Approval notice sent.

2.
Application Type: I485 , APPLICATION TO REGISTER PERMANENT RESIDENCE OR TO ADJUST STATUS

Current Status: Notice Returned as Undeliverable.

COULD YOU PLEASE tell me what is wrong with it. I have been living the same address for more than 7 years.