It must I haven't heard about any Post Office employees being shot by a coworker lately.
Well, at least since January, 2006.
http://en.wikipedia.org/wiki/Patrick_Sherrill
Goleta, California, in 2006
Another incident [1] occurred on the evening of January 30, 2006, at a large postal processing facility in Goleta, near Santa Barbara, California. Police said that Jennifer San Marco, a former postal employee, killed six postal employees, including one critically wounded who later died, before committing suicide with a handgun.
Police later also identified a seventh victim; Beverly Graham, 54, was found dead in a condominium complex in Goleta where San Marco once lived. [2].
The other dead included Charlotte Colton, 44; Ze Fairchild, 37, and Maleka Higgins, 28, both of Santa Barbara; Nicola Grant, 42, and Guadalupe Swartz, 52, both of Lompoc; and Dexter Shannon, 57, of Oxnard.
According to media reports, the Postal Service had forced San Marco to retire in 2003 because of her worsening mental problems. Her choice of victims also may have been racially motivated; San Marco had a previous history of racial prejudice, and tried to obtain a business license for a newspaper of her own ideas, called Racist Times, in New Mexico.
This incident is believed to be the deadliest workplace shooting ever carried out in the United States by a woman.