A mail stop is a location where mail is delivered and collected at large buildings, such as university campuses, government agencies, and major businesses. Generally, it is indicated by a mail stop code, which is often alphanumeric.
While a postal stop code may seem fairly incomprehensible to an outside observer, the mail delivery crew within the facility deciphers the information, typically determining the building, floor, and even the department and desk where the letter must be delivered.
Internal mail within the facility and mail delivered to the facility both utilise mail stop codes. When addressing mail for delivery to a mail stop facility in the United States, include the recipient’s name, mail stop code, department, facility, street address, city, state, and ZIP code.