That Newman character on Seinfeld, portrayed by the talented Wayne Knight, was indeed one of my favorite recurring characters of that series. However, there was a postal 'worker' character from Barney Miller who really set a high bar. In "Uniform Days" (Season 6, Episode 7, 1980) the great Stuart Pankin played the role of Postal Service employee Alex Fleischer, a mail carrier who had no interest in delivering "unneeded" mail.
Pankin played other characters in several episodes. Always a fine performance.
Ⓐ Steve Ⓐ