Editing Letter box (section)

===United States===
[[File:Mailbox in Jacksonville, Florida.jpg|thumb|upright|A [[plastic]] mailbox in [[Jacksonville]], Florida, US]]

The US Post Office has established guidelines for mail recipients, including mail slot or mailbox size, location, and identification requirements.<ref name="Reference7A"/><ref>{{cite web|url=http://pe.usps.gov/Archive/HTML/DMMArchive1209/D041.htm#Xbi4678 |title=US Postal Customer guidelines |publisher=Pe.usps.gov |access-date=2012-09-19 |url-status=dead |archive-url=https://web.archive.org/web/20121004024025/http://pe.usps.gov/Archive/HTML/DMMArchive1209/D041.htm |archive-date=2012-10-04 }}</ref> While the Post Office permitted alternative designs for attached mailboxes and mail slots that met basic size and construction requirements, the same was not true for curbside mailboxes, which postal regulations required be in the form of the traditional dome-rectangular or 'tunnel-top' design first established in 1915. In 1978, seven years after the establishment of the restructured US Postal Service, postal authorities at last approved a "contemporary" mailbox specification for alternative designs.

Currently, US curbside mailboxes are classified as (T) Traditional, (C) Contemporary, or (L) Locking.<ref name="USPS-curb">''[http://about.usps.com/publications/engineering-standards-specifications/spusps-std-7b01/welcome.html U.S. Postal Service Standard Mailboxes, Curbside]'', U.S. Postal Service STD-7B01, retrieved 8 February 2012</ref> Traditional or Contemporary non-locking curbside mailboxes are approved in three sizes - No. 1, No. 2, or No. 3, measured by minimum interior dimensions.<ref name="USPS-curb"/> The largest acceptable curbside mailbox is the No. 3, which measures 22.81&nbsp;inches long, 11&nbsp;inches wide, and 15&nbsp;inches in height (58&nbsp;cm x 28&nbsp;cm x 38&nbsp;cm) at the peak.<ref name="USPS-curb"/> Locking mailbox designs that provide security for the recipient's incoming mail have fewer restrictions on shape and size, though designs with a slot for incoming mail must be at least 1.75&nbsp;inches high by 10&nbsp;inches wide.<ref name="USPS-curb"/> Residential locking mailboxes cannot require the postal carrier to have a key, by USPS Specifications.<ref name="Mail Boss FAQ">{{cite web|title=Mailbox FAQ|url=http://www.mailboss.com/faq#key|work=MailBoss.com|publisher=Epoch Design|access-date=14 June 2013}}</ref>  Therefore, no USPS approved residential locking mailbox has secure outgoing mail. Installation requirements vary from standard unlocked mailboxes: with locking mailboxes, the incoming mail slot must be 41"-45" above the roadside surface, and the front of the mailbox must be 6"-8" back from the curb.<ref name="USPS Specifications">{{cite web|title=USPS Specs|url=http://www.mailboss.com/usps-specs|work=MailBoss.com|publisher=Epoch Design|access-date=14 June 2013}}</ref>  USPS specifications for all mailboxes mandate the same, except the placement of the 'incoming mail area' varies with a locking mailbox.<ref name="USPS mailbox guidelines">{{cite web|title=Mailbox Guidelines|url=https://www.usps.com/manage/know-mailbox-guidelines.htm|work=USPS.com|publisher=USPS|access-date=14 June 2013}}</ref>