Because it's constantly exposed to the elements, a metal mailbox really takes a beating. To rejuvenate yours, remove it from its post and take off the hardware. If it’s rusty, gently scrub it with a wire metal brush and then wipe away debris. Then, shake up some indoor/outdoor spray paint in a formula appropriate for metal and apply it to the mailbox, holding the can about eight inches away. Don’t forget to paint the flag in a bold, contrasting shade so the mail carrier will notice it.