Going Postal: A Novel of Discworld by Terry Pratchett stars petty con man Moist von Lipwig, who has been caught, and is offered hanging or a new job. He takes the job (which beats hanging around) and the Postal ?Service of Ankh Morpork is transformed. Gentle satire from Sir TP.
Available as book or DVD. It's often difficult to choose; with the Discworld it's easy - buy both!