If a mail is done with signature confirmation, does the recipient on the mail need to be there to sign or just anyone receiving it on his/her behalf(a neighbour or a roommate for instance)? Does the post office keep it if the recipient is not there to sign or does it bounce back to sender?

http://faq.usps.com/eCustomer/iq/usps/request.do?create=kb:USPSFAQ&view()=c%5Bc_usps0317%5D&varset(source)=sourceType:embedded

Thanks for the link!