1. Install wall bracket in desired location. Make sure wall bracket is securely fastened to     wall. Align with wood stud or use metal wall plugs to receive screws. Make sure wall     bracket is square and level.

2. Place mailbox cabinet on wall bracket. Align holes in bottom of cabinet with holes in     wall bracket. Shim if necessary to have cabinet sit level on bracket and flush up     against back wall. Drill holes in back panel close to sides. Align with wood stud or use     metal wall plugs to receive screws. One screw in top and botttom corner     compartments and one in every other compartment along sides, top and bottom     should be enough.
    Drill holes from inside of compartments.

3. Secure cabinet by bolting to wall bracket and screwing to back wall through holes     already drilled.