Multiple families living down a single road typically will see multiple mailboxes by the roadside. A more economical and less confusing option is to erect a mailbox stand capable of housing several mailboxes. The stand is a simple pair of posts connected by a sturdy 2-by-6-inch beam with a second beam placed vertically beneath the first for support. The mailboxes are spaced evenly on top with bases anchored to the top rail.
Cut two 4-inch, square beams to the desired height of the stand plus 2 feet with a mitre saw. Cut one 2-by-6-inch beam to the desired length which equals the width of the mailbox, typically 8 inches, plus 6 inches for side clearance, times the number of needed boxes. Cut a second 2-by-6-inch beam to the same measurement minus 8 inches. Cut one 1-by-8-inch wood base for each letter box to the length of the mailboxes, typically 21 inches.
Dig two holes spaced apart by the length measurement used for the 2-by-6-inch beams to a depth of 2 feet with a post hole digger. Place the 4-inch square beams into the holes.
Attach the longer 2-by-6-inch beam to the top of the 4-inch square beams so that the 6-inch side lays flat on top of the posts. Drive three 3-inch, self-tapping wood screws through the beams into the tops of each post with a drill and screwdriver drill bit so that the ends of the beams are flush with the sides of the posts creating a rectangular shape.
Attach the shorter 2-by-6-inch beam vertically spanning between the two posts with the 2-inch edge pressed up against the base of the longer beam to create a support. Drive 3-inch wood screws through the top beam into the side of the lower beam, spacing the screws every 8 to 12 inches. Drive two screws through each end of the beam into the sides of the posts at an angle to the posts.
Mount the 1-by-8-inch planks on top of the top beam with one flush with each edge and pointing in the direction the mailboxes will face. Evenly space the units so that there's room to reach between them with a screwdriver or drill when mounting the mailboxes. Drive three screws through the top of each plank into the top beam.
Attach the mailboxes to the planks with screws driven through the pre-drilled holes in the base of the mailbox into the wood planks. Work from one side to the other. Place one screw through each pre-drilled hole into the sides of the wood planks.
Mix and pour cement into the holes for the posts to within a few inches of the top of the holes. Hammer ground stakes around the structure. Tie ropes to the structure and to the ground stakes. Hold a level against the structure to obtain the proper level. Adjust the ropes as necessary to hold the structure stable while the concrete sets. Leave the ropes and stakes in place for 24 to 72 hours. Back-fill the holes with dirt once the concrete sets.