All finance executives are under the gun these days as they navigate the minefields of the credit crisis and a global recession. But even in the current environment, Joe Corbett faces a particularly nettlesome set of problems.

Corbett is CFO of the U.S. Postal Service, whose $70 billion in 2008 revenue ranks it as roughly the 25th largest U.S. company. But its revenue is suffering these days as mail volume, already under pressure from the long-term trend toward electronic communication, swoons amid the economic slowdown. In the first three quarters of the Postal Service's current fiscal year, mail volume declined by 20 billion pieces, down 12.6% from the same period last year. The Postal Service expects to have accumulated a deficit of $7 billion by its Sept. 30 year-end and estimates it will then face a $700 million cash shortfall.

"The financial problems are very, very serious," says Corbett, noting that the Postal Service also cut costs by almost as much, more than $6 billion this year.