Letter box

A letter box, letterbox, mail slot, or mailbox is a receptacle for receiving incoming mail at a private residence or business.

Letterboxes or mailboxes consist of four primary designs:

  • a slot in a wall or door through which mail is delivered
  • a box attached directly to the house
  • a box mounted at or near the street
  • a centralised unit consisting of many individual mailboxes for an entire building or neighbourhood


Almost all buildings in the United Kingdom feature letterboxes. In the U.S.A, such receptacles are referred to as mail slots, and are primarily found in older neighborhoods and on the East Coast of the country. These are commonly horizontal slots approximately 12 in × 2 in, found in the middle or lower half of a front door. Most are covered by a flap on the outside to offer a degree of weatherproofing. The flap may by sprung to prevent it opening and closing noisily in the wind; some letterboxes also have a second flap on the inside to offer further protection from the elements. There may also be a small cage or box mounted on the inside of the door to receive the delivered mail.

In many areas of Canada and some older neighborhoods in the U.S.A., wall-mounted or 'attached' mailboxes may also be used in place of mail slots, usually located close to the front door of the residence.

Rural and some suburban areas of North America may utilize curbside mailboxes. These receptacles generally consist of a large metal box mounted on a support designed primarily to receive large quantities of incoming mail, often with an attached semaphore flag to signal the presence of outgoing mail to the mail carrier.

A number of postal services around the world are adopting neighborhood or community mail delivery, in which recipients retrieve their mail from an individual letterbox at a centralised or community mail delivery station located in their building or immediate neighbourhood.

A number of designs of letterboxes and mailboxes have been patented, particularly in the United States.



Private letterboxes or mail slots did not become popular in most of Europe until the mid to late 1800s, although they were used in Paris, France from the late 1700s.

In 1849, the British Post Office first encouraged people to install letterboxes to facilitate the delivery of mail. Before then, letterboxes of a similar design had been installed in the doors and walls of post offices for people to drop off outgoing mail. An example of such a wall box (originally installed in the wall of the Wakefield Post Office) is dated 1809 and believed to be the oldest example in Britain.

North America

In 1863, with the creation of Free City Delivery, U.S. postal carriers began delivering mail to home addresses. During the nineteenth and early twentieth centuries, mailmen knocked on the door and waited patiently for someone to answer. Efficiency experts estimated that each mailman lost 1.5 hours each day just waiting for patrons to come to the door. Slowly, homeowners and businesses began to install mail slots (letterboxes) to receive mail when they were either not at home or unable to answer the door.

Attached mailboxes are common in urban and older suburban neighbourhoods and in high-density neighbourhoods in North America. They are especially common in urban and suburban areas of Canada, where the curbside mailbox is rarely seen except in rural areas.Attached mailboxes are less common in newer developments and in smaller towns and cities where mail is distributed through a combination of post office boxes and community mail stations.

To reduce the time required for the mail carrier to complete delivery when the front door is some distance from the street, it was proposed that individual residential or commercial mailboxes be mounted curbside on suitable posts or other supports, particularly in rural areas. In the U.S.A, curbside mailboxes were originally seen as a method of solving the problem of delivering mail with limited numbers of mail carriers using horse-drawn wagons (and later, motor vehicles) to many widely-scattered rural customers. Before the introduction of rural free delivery (RFD) by the U.S. Post Office in 1896, and in Canada in 1908, many rural residents either had no access to public mail delivery, or had to pick up their mail at a post office located many miles from their homes. Consequently, curbside mailboxes did not become popular in North America until free home mail delivery was an established service. Even then, farmers and rural homeowners at first resisted the purchase of dedicated mailboxes, often using empty bushel baskets, tins, and wooden boxes in which to collect their mail. Not until 1923 did the U.S. Post Office finally mandate that every household have a mailbox or mail slot in order to receive home delivery of mail.

Curbside 'full-service' mailboxes were soon fitted with a signal flag or semaphore arm - usually red or fluorescent orange. Originally, this flag was raised not only by the resident of the property to notify the postman of outgoing mail, but also by the postman to inform the recipient that incoming mail had been delivered - a considerable convenience to all during periods of severe weather.

In 1915, the iconic U.S. curbside mailbox with its curved, tunnel-shape top (to prevent water and snow collection), latching door, and movable signal flag was designed by U.S. Post Office employee Roy J. Joroleman.Joroleman's design, approved by the U.S. Postmaster General, was eventually released free of charge by the Post Office for inexpensive duplication by mailbox manufacturers; it has been the top-selling U.S. curbside mailbox ever since, and was widely adopted by rural residents in Canada as well. The Joroleman mailbox has been both exalted as a supreme manifestation of American functionalist industrial design, and excoriated by others as a 'Quonset hut on a stick'.

In the U.S. and Canada, rural curbside mailboxes may be found grouped together at property boundaries or road/driveway intersections, depending upon conditions. Although the USPS has general regulations stating the distance a letter box may be from the road surface, these requirements may be changed by the local postmaster according to local environment and road conditions. As of 2004, nearly 843,000 rural Canadian residents used curbside mailboxes for private mail delivery, though Canada Post has since announced plans to cut individual mail delivery services to rural residents.

In order to promote uniformity, as well as the convenient and rapid delivery of the mail, the United States Post Office Department, (later the United States Postal Service, or USPS) has always retained authority to approve the size and other characteristics of all mail receptacles, whether mailboxes or mail slots, for use in delivery of the U.S. mails, and issued specifications for curbside mailbox construction for use by manufacturers. Approved mailboxes from the latter are always stamped U.S. Mail and Approved by the Postmaster General. These standards have resulted in inevitable limitations on product diversity and design, though new materials, shapes, and features have appeared in recent years.

Since 1971, steady increases in postal service costs have motivated the USPS to insist on either curbside or centralized mail delivery for new suburban neighborhoods and developments. A 1995 cost delivery study published in a USPS Operations handbook listed per-address annual delivery costs as: Door-to-door, $243; Curbside, $154; Cluster Box (centralized mail delivery), $106.

Recent Developments

In 2001, the USPS first approved designs for locking curbside mailboxes to stem a rise in mail and identity theft. With these secure designs, the incoming mail is placed into a slot or hopper by the mail carrier, where it drops into a secure locked compartment for retrieval by the homeowner (who retains the only key or combination to the lock). Because of the increased risk of vandalism to curbside mailboxes, various vandal-resistant boxes made of resilient plastics or heavy-gauge steel or aluminum plate have also entered the market.

A property containing several homes, apartments, condominiums, or businesses may utilize a community mail station (NDCBU, or Neighborhood Delivery Collection Box Unit), commonly known as a cluster mailbox. These units have multiple compartments for the centralized delivery of mail to the residents of a building or an entire neighborhood, instead of door-to-door or curbside delivery. A parcel locker for receipt of packages and a separate compartment for outgoing mail are usually built into the station. The mail carrier will have a key to a large door on one side that reaches all the compartments, and the residents or tenants will each have a key to the door into their individual compartment on the other side. Recently, the USPS and Canada Post have engendered controversy by aggressively promoting community mail stations or cluster box installations in new suburban developments and some urban and rural areas as well. KopparStaden AB, a housing cooperative in Falun, Sweden, has begun to install centralized mail stations with individual letterboxes using electronically-operated doors in its buildings.


The European standard for letter boxes, EN 13724:2002 "Postal services – Apertures of private letter boxes and letter plates – Requirements and test methods", replaces earlier national standards such as BS 2911:1974 "Specification for letter plates" or DIN 32617. It specifies among other things:

  • that envelope size C4 (229 mm × 324 mm) must be deliverable without bending or damage;
  • that the internal volume must able to hold at least a 40 mm high bundle of C4 envelopes;
  • an aperture width of either 230–280 mm (> C4 width) or 325–400 mm (> C4 height);
  • an aperture height of 30–35 mm;
  • a mounting height of between 0.7 and 1.7 m for the aperture;
  • and various privacy, theft-protection, rain protection, vandalism resistance and corrosion-resistance test requirements.

In the U.S.A., the USPS also has established postal delivery guidelines for its various residential and business customers, including mailbox size, location, and identification requirements.


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