When doing so, you must include the P.
Write your return address in the same format as the address block. The more accurate the address, the better. Thus, the first address is valid and the second one is not.
Below the name, include a business name, if applicable. Since both are valid, and the physical address is listed first, the letter will be delivered to the physical address. Box By Kirsten O'Hara A Post Office Box is a beneficial option for someone who is in the middle of moving from one location to another; someone who has concerns about the privacy of her home address; and for businesses.
PO Box E.