can a po box be a return address
In postal mail, a return address is an explicit inclusion of the address of the person sending the message. It provides the recipient (and sometimes authorized intermediaries) with a means to determine how to respond to the sender of the message if needed. The return address need not include a sender's name, but should include address or P.O. box details in the same way as the delivery address should. In some countries, the return address is conventionally located in the upper left hand corner of the envelope, card, or label. In the United Kingdom, the return address is usually placed on the reverse of the envelope, near the top.
Return address