Ankh-Morpork Order of Postal Workers Benevolent and Friendly Society
The Ankh-Morpork Order of Postal Workers Benevolent and Friendly Society is a society of postal workers based in the main branch of the Ankh-Morpork Post Office. They are described as not being so much of a secret society, as just an ignored one.
Their function is described as being "about pensions" and giving proper funerals to old Post Office employees when they're Returned to Sender. Their initiation ritual is known as the Postman's Walk and involves braving many dangers to deliver the post. Moist von Lipwig manages to brave the dangers of the walk and emerge as official, Order-approved Postmaster.