Seems the post office is having financial problems.
In E-Mail Age, Postal Service Struggles to Avoid a Default - NYTimes.com:
"At the same time, decades of contractual promises made to unionized workers, including no-layoff clauses, are increasing the post office’s costs. Labor represents 80 percent of the agency’s expenses, compared with 53 percent at United Parcel Service and 32 percent at FedEx, its two biggest private competitors. Postal workers also receive more generous health benefits than most other federal employees."
Looks like Scott Walker needs to step in to fix the postal service.