Last year I bought this mailbox light. You stick it inside your mailbox (it's got peel-off sticky tape). Two sensors - light and motion - sense what's happening. If they sense darkness and no motion (door closed) nothing happens. If they sense light and motion (opening the box in the day) nothing happens. If they sense darkness and motion (opening the box at night) the light goes on for a couple of minutes, allowing you to see the mail.
It runs on 3 AAA batteries, which last months. When it is time to change the batteries, just pull on the case to release it from the magnetic back cover (which is attached to the mailbox with the sticky tape).
At 2 for $15 (give one to a friend or install in a cabinet) this is worthwhile convenience.
