Posty, also known as Fetchy or Boxy, is a sentient robot built by Gyro Gearloose.
Seeking to avoid having to go out to collect his mail, which was a constant interruption of his experiments, Gyro Gearloose decided to build a two-legged mailbox that would bring the mail inside his house as soon as it was delivered; thus, Posty, a sentient robotical mailbox, was born.
Alas, Gyro, as is typical of him, had not thought everything through. Posty quickly became bored with his job of standing in front of his master's house, perfectly still, until the mail was delivered, and so he began to play pranks on passers-by. Even after Gyro got him to behave, Posty did not work as intended, as the mailman was much too scared of a living mailbox to deliver the mail at all.