Mailbox is a main character in Blue's Clues.
Mailbox lives at the foot of the pathway in front of the Blue's Clues house. He likes to make others laugh and wants to become a comedian when he grows up. He speaks with a thick New York accent. Mailbox sits on a post outside when he is not delivering the mail. When he has a letter for Steve or Joe, he uses an extension arm to enter through the living room window to the right of the Thinking Chair. His extension arm is impractically long and can transport him anywhere.
Mailbox's favorite hobbies are delivering letters and telling jokes. In almost every episode, Steve or Joe sing a special song ("Mailtime") before Mailbox delivers a letter. On some rare occasions such as in "Blue's Big Pajama Party," Mailbox makes a special nighttime mail delivery. Mailbox's catchphrases are "Mail's here, mail's here!" and "You're welcome!"
Mailbox is mostly dark purple. When he is shown outside, he is usually positioned on a long post, which was purple in earlier episodes and the opening sequence, but starting in "A Snowy Day", it became black (though it was still purple in the opening sequence until Season 4 and in some books). He has a pair of white eyes with black pupils and a pink mouth. He also has a pink flag and a small purple bolt connecting it to the rest of his body.
Mailbox appears in every episode of Blue's Clues with the exception of "The Legend of the Blue Puppy". His first appearance was in the pilot episode, "Blue Prints". His last appearance was in "Meet Blue's Baby Brother" episode of Blue's Room.