What size mailbox cover will fit my mailbox? There are two sizes of mailbox covers. Choose Standard Size or Large Size Mailbox Covers. Be sure to select the right size mailbox covers to fit your mailbox. There are two sizes of Mailwraps mailbox covers to choose from: Standard Size and Large Size. Mailwraps are a clever way to quickly turn your mailbox into a work of art, so let's find out [...]