Quick Service Guide 602 - Basic Addressing Standards
There are special addressing services you can use to tell the Postal Service what to do with your mail if it can’t be delivered. You may want your mailpiece forwarded to a customer who has moved or you may want the piece back with a corrected address on it. These special addressing services are called ancillary service endorsements.
--You are welcome to put logos and slogans on your mailpiece. Just be careful where you put them. Don’t put anything below the delivery line of the delivery address.
--We recommend 8 point or larger font size for the return address.
Special Addressing Service (Ancillary Service Endorsements)