2 Del. Admin. Code § 7.4
No mailbox or newspaper delivery box (hereafter referred to as mailbox) shall be allowed to exist on the State-maintained roadway right-of-way if it interferes with the safety of the traveling public or the function, maintenance, or operation of the State-maintained roadway. A mailbox installation that does not conform to the provisions of this regulation is an unauthorized encroachment.
A mailbox installation that conforms to the following criteria shall be considered acceptable unless, in the judgment of DelDOT, the installation interferes with the safety of the traveling public or the function, maintenance, or operation of the State-maintained roadway.
No mailbox shall be permitted where access is obtained from the lanes of a freeway or where access is otherwise prohibited by law or regulation.
On curbed streets the roadside face of the mailbox shall be set back from the face of curb distance between six and eight inches. On roadways without curbs or all-weather shoulders and which carry low-traffic volumes operating at low speeds, the roadside face of a mailbox shall be offset between eight and twelve inches behind the edge of pavement.
Where a mailbox is located at a driveway entrance, it shall be placed on the far side of the driveway in the direction of the delivery route.
Where a mailbox is located at an intersecting road it shall be located a minimum of 100 feet beyond the center of the intersecting road in the direction of the delivery route. This distance shall be increased to 200 feet when the average daily traffic on the intersecting road exceeds 400 vehicles per day.
Mailboxes shall be of light sheet metal or plastic construction sized to conform to the requirements of the U.S. Postal Service. Newspaper delivery boxes shall be of light sheet metal or plastic construction of minimum dimensions suitable for holding a newspaper.
No more than two mailboxes may be mounted on a support structure. Lightweight newspaper boxes may be mounted below the mailbox support.
A single 4"x 4" square or 4.5" diameter round wooden post or a metal post with a strength no greater than a 2" diameter standard strength steel pipe and embedded no more than 24" into the ground shall be acceptable as a mailbox support. A metal post shall not be fitted with an anchor plate, but it may have an anti-twist device that extends no more than 10" below the ground surface. Mailbox supports shall not be encased in concrete or brick.
The post-to-box attachment details should be of sufficient strength to prevent the box from separating from the post top if the installation is struck by a vehicle.
The minimum spacing between the centers of support posts shall be three-fourths the height of the posts above the ground line.
Any mailbox that is found to violate the intent of this regulation shall be removed by the postal patron upon written notification by DelDOT.
At the discretion of DelDOT, based on an assessment of hazard to the public, the patron shall be granted not less than 24 hours or more than 60 days to remove an unacceptable mailbox. After the specified removal period has expired, the unacceptable mailbox shall be removed by DelDOT, at the postal patron's expense.
2 Del. Admin. Code § 7.4
15 DE Reg. 551 (10/01/11)
16 DE Reg. 1199 (5/1/2013)
18 DE Reg. 240 (9/1/2014)
18 DE Reg. 709 (3/1/2015)
19 DE Reg. 938 (4/1/2016) (Final)