The United States Postal Service has specific requirements for all residential curbside mailboxes. The USPS Domestic Mail Manual sets forth regulations and rules concerning residential curbside mailboxes. The manual describes the standards for letterboxes and other mail receptacles for the deposit or receipt of mail.Residential Mailboxes A residential mailbox is any curbside or wall-mounted receptacle that is used for the purpose of receiving material in which postage is paid.Who Can Use A Mailbox Only authorized letter carriers may place mail or packages into the mail receptacle.

Post Office Mailbox Requirements

No part of the mail receptacle may be used to deliver anything that does not contain postage. This includes items attached to the box, hung from the box or inserted into the mailbox. Any mailable material not displaying postage and found in the mailbox is subject to the same amount of postage as if it were carried by a mail carrier.Exclusions from USPS Rules Door slots and other non-lockable bins used with apartment mailboxes are subject to the same regulations as a curbside mailbox. Just keep in mind that a mail slot should be large enough to accommodate the type of mail the homeowner receives. If the mail slot is not large enough, then the mail carrier will cease delivering mail to the residence.

Curbside Mailboxes All homeowners must keep the area around their mailboxes clear of anything that will obstruct the safe delivery of mail. If the United States Postal Service employee cannot safely reach in and deliver the mail, the postmaster may withdraw delivery to that mailbox.Any curbside mailbox which is to be installed at the edge of the roadway or curbside of the street and allows it to be served by a mail carrier from a vehicle on any city route, rural route or highway must be approved by the United States Postal nowEvery curbside mailbox should display the homeowner’s name and address assigned by the local authorities on the flag side of the mailbox.

The numbers and letters must be at least one inch high and in a contrasting color in neat, legible letters. If the boxes are grouped and the address cannot be placed on the flat side of the mailbox, then the house number should be inscribed on the door. No advertising of any kind can be placed on the mailbox or the mailbox post.

Mailbox Sizes

Mailbox Sizes There are regulations regarding curbside mailboxes. A curbside mailbox can be one of three sizes for residential mail: small T1 (C1) size is approximately 5 inches wide by 6 inches tall and 18 ½ inches long, Medium T2 (C2) size is approximately 6 inches wide by 7 inches tall by 19 inches long, and the Large T3 (C3) size is approximately 8 inches wide by 11 ½ inches tall by 22 ½ inches long. The “T” stands for Traditional and the “C” stands for Contemporary. The dimensions reflect the minimum interior size.