Hi, welcome to Super Adventures. I'm Ray Hardgrit and I know absolutely nothing about the first Postal game. I've played a lot of Postal 2 and I've heard that Postal 3 is so bad that developer Running With Scissors basically disowned it (in fact it's so bad that they added the game box into Postal 2 and you get an achievement for pissing on it), but the original Postal remains a mystery to me. I'll soon fix that though.
(Fair warning: there's a good chance I'm going to end up calling the game 'Portal' instead of 'Postal', and it likely won't just be once, so try not to be confused if you catch me screwing up.)