Mail Man is an achievement in Mafia II.
Requirements[]
Sell all the gas stamps before the time runs out.
Walkthrough[]
You will receive this in Enemy of the State; you need to sell the stamps to six gas stations in Empire Bay before the timer runs out.
The stations will be highlighted on your map with a red marker. One way to proceed is to visit the two in Little Italy first, then the one in Chinatown, Oyster Bay, West Side, and finally Sand Island.