There are sixteen levels in the base game of POSTAL seventeen if the Elementary School is counted), four additional levels (EZ Mart, Shanty Town, Earthquake and The Resort) were added in the Special Delivery add-on, two more levels (Tokyo and Osaka) in Super POSTAL, and another two additional levels (The Carnival and The End) created specifically for Redux.
Each has a quote from the Postal Dude, with the entries for Tokyo and Osaka done in haiku form.
In addition to the quotes, the original POSTAL manual had a set of diary entries which the Postal Dude refers to as his "War Journal" after the fourth level. These entries would be re-used in POSTAL Redux for the game's hard mode along with new entries for the add-on and Redux exclusive levels. Unlike the previous quotes, there are no dates on the war journals.
10/17/1997 The Earth is hungry. Its heart throbs and demands cleansing. The Earth is also thirsty.
10/17/1997 Blessed are the meek for they make easy targets.
10/17/1997 The air ripens with the odors of the dead and dying. It smells like...victory.
10/18/1997 A glorious symphony of slaughter! 76 tromboners led the death parade...
10/18/1997 Life is cheap--death is free! Act now! Supplies are limited! (Offer void in Arizona)
10/18/1997 Furious fireflies materialize against the cavern wall and sunder the earth into dust. Come, little insects, and see the web WE'VE woven!
10/19/1997 I will don the eviscerated organs of my enemies as party hats, wear their shredded entrails as neckties, and oh, how I shall dance!
10/19/1997 Human trash spills from its containers as death rains down upon them, sweeping the streets in a cleansing cloudburst of blood...
10/19/1997 Next stop: Armageddon, the River Styx, Hades... and all points in between! All aboard!
10/20/1997 Feathers will fly, but big birds won't. They WILL however, be going south this winter...FAR south!
10/20/1997 Blood splinters everywhere. Like a river, flowing around me, pulling me in its wake. Paradise! Prepare for...deconstruction!
10/20/1997 Black leather smoke coils up my nostrils tingling with death's surprise. Human remnants cling to my clothing like bloody briars as I continue to wade, hip deep in flesh, bone and viscera. Bad neighborhood coming up!
10/21/1997 I am the celestial gardener, policing the planet of the stink weeds and poisons which leak out even through the cracks in the cold asphalt sidewalks of the City of Sin!
10/21/1997 No day in the park. Too much of the blood on me is mine. But the day is not done, and I've miles to go to make them sleep...Peanuts anyone?
10/21/1997 Feast upon the frozen images of molten massacre as the machineries of death grind relentlessly, mindlessly on...
10/22/1997 From the halls of the Vatican to the Runways of Truth, we are there. At the place called Climax, and the time called NOW. When it's done, let the gods sort it out!
1/20/1998 Watch for falling prices, falling employees, falling customers, incoming missiles, and blood puddles...
1/22/1998 The earth is thirsty. It also seems to have soiled itself...
1/21/1998 The earth was hungry, so it ate some people.
1/23/1998 Did someone say they've fallen and can't get up?
10/20/1999 Watch the river run; flowing with bubbling blood; the end, it is near.
10/20/1999 The footprint you see; Godzilla has formed for you; your city laid waste.
10/23/1997 The hive has been cleansed. The source of the corruption has been corked, laid in a body bag and dragged to the outskirts of existence...
The levels were referred to as "Realms" in the original level editor. This is shown by their file extension being "rlm".
In the original game, the diary quotes' year is marked as 1997 for the base levels, 1998 for the Special Delivery levels, and 1999 for the Super Postal levels. In POSTAL Redux, they're instead marked as 2017 for the base levels, 2018 for the Special Delivery levels, and 2019 for the Super Postal levels. The End is not marked with a date at all.
While the Elementary School plays out as just a cutscene in-game, earlier versions of POSTAL had a "Load Level" option allowing one to load the map but the map is unbeatable as the school children are invulnerable, and there are no hostiles to up one's kill percentage.
In an interview, Vince Desi revealed that some of the diary entries came from a childhood notebook though he may have said this in jest.