Does Your Mailbox Need to be Replaced Here in Minnesota? Get our free mobile app If your mailbox has seen better days, this might be the week you want to replace it here in Minnesota. I'm just going to guess that you didn't know there's an entire week devoted to mailboxes, right? I didn't, either, until I saw this note from the U.S. Postal Service regional office in Minneapolis. And, as it turns out, that week is THIS week-- because it's something the Postal Service refers to as 'Mailbox Improvement Week.' According to the release, Mailbox Improvement Week, which is always the third week of May exists "...to encourage customers to examine and, where necessary, improve the appearance of their mailboxes. Neat, sturdy and attractive mailboxes make a significant contribution to the appearance of the streets and homes," the released noted.