The Ankh-Morpork Post Office Handbook - Stephen Briggs

The Post Office: this musty, dusty and sh***y organisation was jolted back into life in GOING POSTAL. Hidebound and rulebound, the Post Office is creaking towards a brave new world of efficiency - and it may even deliver the mail, too. But like all bureaucracies, the Ankh-Morpork Post Office has its rules and regulations and these, together with the history of this once-great department, are highlighted and parodied in the Ankh-Morpork Post Office Handbook.
How do you send eggs through the Post Office? What size envelope is banned? And what happens when snails start eating the mail? It's all here in the Ankh-Morpork Post Office Handbook and Diary 2007.
* that's of the pigeon guano type, of course.