Mail with a dual address (both a street address and a Post Office box number) is delivered to the address immediately above the city and state (or to the Post Office box if both the street address and Post Office box are on the same line). If a ZIP+4 code or 5-digit ZIP Code is used, it must correspond to the address element immediately above the city and state (or with the Post Office box number in the address if both the street address and Post Office box are on the same line). These restrictions also apply to return addresses on mail.
More Than One Post Office
Mail with the name of more than one Post Office in the delivery address or return address is not acceptable for mailing.
Mail Addressed to CMRAs
Mail sent to an addressee at a commercial mail receiving agency (CMRA) must be addressed to their private mailbox ("PMB" or "#") number at the CMRA mailing address.