Going Postal (Discworld Novel 33) by Terry Pratchett

Imprisoned in Ankh-Morpork, con artist Moist von Lipwig is offered a choice: to be executed or to accept a job as the city’s Postmaster General.

It’s a tough decision, but he’s already survived one hanging and isn’t in the mood to try it again. The Post Office is down on its luck: beset by mountains of undelivered mail, eccentric employees, and a dangerous secret order. To save his skin, Moist will need to restore the postal service to its former glory, with the help of tough talking activist Adora Belle Dearheart.

Who happens to be very attractive, in an ‘entire womanful of anger’ kind of way. But there’s new technology to compete against and an evil chairman who will stop at nothing to delay Ankh-Morpork’s post for good . . .