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Whether you are sending a business letter or a wedding invitation, the envelope is the first thing the person will see. Therefore, it is important that you format the mailing address correctly. The most important etiquette to follow is set by the U.S. Postal Service—because if they don’t understand it, they can’t deliver it. Beyond that, there are certain protocols that are deemed more “proper” than others.

Abbreviations

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Formal mailing address etiquette states that the only abbreviations on the envelope are Mr., Mrs., Ms., Dr. and Jr. All other words (including the state) should be spelled out. The USPS does allow for abbreviations. For a complete list of USPS-approved abbreviations, check out the "Resources" section below.

Names and Titles

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The first line of the address will be the person’s name. Again, don’t abbreviate or use nicknames. It should be “Robert,” not “Bob” or “Bobby.” Married couples where the wife has kept her maiden name and unmarried or same-sex couples who live together should be listed separately in alphabetical order by last name. For example, if sending an invitation to Tim Doe and Jane Smith, the first line would say “Mr. Timothy Doe” and the second line would say “Ms. (Miss/Mrs.) Jane Smith.” Never include the words “and guest” or “and family” on the outside envelope.

Business Invitations

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If you are sending a business invitation, then the first line would be the person’s name and the second line would be the business where the person works. Always send business invitations to the person’s place of business and not the person’s home.

Street Address

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The second or third line (depending on whether you have one or two names) should be the street address. Spell out single street numbers (1-9) but use digits for street numbers above 9. Streets that are numbers can be written as numbers or words. For example it could be “124 North Twenty-third Street” or “124 North 23rd Street.”

City, State and Zip Code

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For formal addresses, write out the city and state. However, the words "mount" and "saint" can be abbreviated as “Mt.” and “St.,” respectively. The USPS prefers that no punctuation is used. However, most people feel that a comma should be included between the city and state.