The lock bolt is in the mailbox does not always withstand the encroachment of the feeder bullies. Too primitive its form is thin and the iron from which it is made.
But if you replace the stock bolt with steel plate cross-section 20×3 mm, bent as shown, so just the box, no one will open.
Recommend to read
THE KEY IS IN THE IGNITION
When working with a power drill often lost the key to her patron. He will always be on hand if you tape it with electrical tape to the cord at a distance of 0.5...0.6 m from the arm. ...
MODEL MISSILE BOATS
The model of modern missile boats (Fig. 1), developed by the Central marine club DOSAAF intended for competitions. The housing (Fig. 2) is made movable. In the drawing, the...