Complex sentence: A post town is a required part of all postal addresses in the United Kingdom, and a basic unit of the postal delivery system.Including the correct post town in the address increases the chance of a letter or parcel being delivered on time.
Split into simpler sentences: A post town is a required part of all postal addresses in the United Kingdom, and a basic unit of the postal delivery system. Royal Mail, "Address Management Guide," (2004) Including the correct post town in the address increases the chance of a letter or parcel being delivered on time.