Did the article mention prefunding retirments? If not, they are missing the biggest part of the pie.
"We are required to make this $5.5 billion dollar payment into the future retiree health benefits fund, and probably won't be able to make it when it comes due September 30th."
Postal Service spokeswoman Yvonne Yoerger said at that hearing, Postmaster General Patrick Donahoe will insist that the fund be re-scaled from the days when there were 900,000 people on the payroll. The mandated funding level has not changed in the years since then, although the Postal Service has trimmed 250,000 jobs.
She said "the fact is, no other government agency, and few corporations in the private sector are required to fund retiree health benefits 75 years out."
So the US Postal Service is STILL required to pay into a fund covering the retirement benefits of 250,000 workers WHO DON'T EXIST.
My opinion is that there are some lawmakers in the US who quite simply want the Postal Service to go belly up since (according to their political philosophy) they want a free-market postal system. Hence they burden it with a nonsensical funding requirement so as to make it look like it is loosing money hand over fist.