Air mail involves a longer transit time, so taking care to address the envelope properly will reduce delays or undeliverable letters. An international post will need to be processed by the sender's country and the recipient's national postal service. The format for processing an international envelope is slightly different from the format for domestic mail. Include your return address in the same international format in case the receiving country has problems processing the mail. Printed (instead of cursive) writing enhances legibility.
Write the full name of the recipient as the first line of the address. Positioning the first line slightly above the center of the envelope to give yourself enough room for the complete address.
Write the street address or post office box number for the second line. If applicable, write the second line of the street address or the apartment number below the second line (line 2A).
Write the city or town; and subdivision, province or county; and postal code on the third line.
Write the country in capital letters on the fourth line.
Write your return address using the same format above (four lines) in the upper left corner of the envelope.