Listen to The Key's in the Mailbox online. The Key's in the Mailbox is an Unknown language song and is sung by Freddie Hart. The Key's in the Mailbox, from the album The Rebellious Jukebox Plays the Big Hit Country Tunes of 1960, was released in the year 2008. The duration of the song is 2:45. Download Unknown songs online from JioSaavn.