All mail boxes have a flag to tell the mailman that there is mail to be picked up. However, if you don't have any outgoing mail and the flag raised, how do you know when the mail has been delivered without walking all the way to the mailbox to check?
This is the absolute cheapest and easiest method possible. Simply create a flag that pops up when the mailbox door is opened. I have made these with stainless steel spring wire and metal coat hangers. Either works, coat hanger is cheaper and available, stainless steel wire is harder to find but will last for decades.
Step 1: WHAT YOU NEED
Coat hanger or stainless steel wire
Needle nose pliers or suitable substitute
Couple of machine screws with nuts
Fishing swivel or more wire
Step 2: Bend One End
Cut the wire to about 1.3 times the
length of your mailbox and bend a sort of safety pin hook in one end.
Make sort of a figure 8 or 2 hole bend at the other end of the wire with openings just big enough to get a machine screw through the hole.
Step 4: Dangly Thing
Add a fishing swivel or piece of wire with some kind of dangly thing. Could be a small fishing lure, a large bead, a wine cork, anything that will hang on the end and be captured by the closing of the mailbox door.
Step 5: Attach to Mailbox
Attach the wire to the back of the mailbox with the machine screws and nuts.
Step 6: Add Flag
Add ribbon, bright plastic tape, whatever will show up from as far away as you are able to see the mailbox.
Step 7: Capture the Flag
Capture the dangly thing when you close the mailbox door. Depending on what your dangly thing is, you might have to grind or file a slot in the lip of the door for it to be able to close properly. Don't make a slot in the body of the mailbox or your dangly thing might get caught and not pop up the way it is supposed to.
Step 8: Mail Has Been Delivered Cause I See the Flag
When the mailman opens the mailbox door, your new Mail Delivered flag will pop up and you can see it from your house. Hope this saves you a lot of wasted time and energy.