Publication 28 - Postal Addressing Standards > 2 Postal Addressing Standards > 21 General > 215 Dual Addresses
Eliminate dual addresses on the output mailpiece, if possible, although mailer files (shown below with dotted lines) may maintain both mailing and physical addresses. However, if dual addresses are used, place the intended delivery address on the line immediately above the city, state, and ZIP+4 Code. Normally, this is the Post Office Box address. The other address must be placed on a separate line above the Delivery Address Line. The ZIP+4 Code used must be the correct code for the delivery address on the line directly above the city, state, and ZIP Code.