The door to your mailbox is your first line of defense against mail fraud and identity theft, so it is well worth your while to make sure that the hinges on your mailbox keep the door closed on your personal and private mail. Hinges that are too loose will constantly have your mailbox door falling open and leaving the mail exposed. Hinges that are rusted or too tight will make life hard on your mail carrier and may result in you not getting your mail in a timely fashion. Either way, following a few easy steps to replacing your mailbox's hinges can solve the problem.
Determine that the hinges are the actual cause of the problem. Check to see if the hinges are too loose (the door keeps falling open even when shut properly) or too tight (the door will not open with a single pull even though nothing is binding the door). Often times mailbox doors get bent out of shape, especially the aluminum doors, and this will cause the door to fit the box improperly and cause symptoms similar in nature to those attributed to faulty hinges. If the door is the problem, it will require either being bent back into shape or replacing the entire mailbox door. If you identify that the problem is caused by the hinges, you can proceed to replace them.
Measure the size of the hinges on your mailbox. Most mailbox hinges are of the one inch variety, though this can vary with the style and make of the mailbox. Pick up a pair of hinges of the appropriate size at your local hardware or home improvement store.
Unscrew the old hinges from the mailbox. Take caution when doing this as many varieties of mailboxes have spring-loaded hinges that may pop out of place as the screws are loosened.
Install the new hinges in the same place where the old hinges were removed from. If the hinges are spring-loaded, insert the springs as instructed in the accompanying directions at this point as well.
Test out the new hinges, applying graphite based spray lubricant if needed to allow for a smooth range of motion. Adjust as necessary in order to prevent any scraping or binding along the edges.