The address must include, in this order: The name of the sender. The shipper's building number and street name. A suite or apartment number, if necessary. The sender's city, state, and zip code. For a, Write your full name, optional business name, mailing address 1 - city, state, zip code and country for international mail. Place the return address in the, Here's how to correctly write a co address on an envelope or package: Start with the recipient's name: Write the full name of the person you are sending the mail to on the first line of the block d 'address. Include co on the second line: After the recipient's name, write co, or in care of, and the name of the entity or person. Address line 1. The next line will be the first line of the address, which corresponds to the specific building number and street name. Address line two. Sometimes two lines are required for an address. For example, if you are targeting a specific suite number or mailbox, it will go here. Last line.PO boxes differ from regular addresses because you do not need to write the postal address. Instead, you write the PO box number when addressing the envelope or package. However, some people still list the street number and name above the PO box number. PO Boxes help individuals and businesses receive mail items at different locations. Here are the steps you can follow to write an address in a business envelope: 1. Include the recipient's name on the top line. You can start the address line in the center of the front of the envelope. Before a person's name, it may be more appropriate to add an honorific prefix such as Mr. or Mrs.