Write the recipient’s name on the first line
Add the street address on the next line (include apartment/suite/unit number)
Add the city, state/province, and ZIP/postal code on the next line
For international mail, add the country name on the last line
Use standard abbreviations for state/province (when applicable)
Keep the address parallel to the longest side of the envelope
Use clear, legible handwriting or printed labels
Leave a blank area in the top-left corner for postage (and return address if needed)
Write the return address in the top-left corner using the same format (name, street, city/state/ZIP, country if applicable)
Example (US):
John A. Smith
1234 Main St Apt 56
Springfield, IL 62704
Example (International):
Maria Gonzalez
Calle de Alcalá 123, 4ºB
28009 Madrid
Spain