What does the U.S. Postal Service do when its customers complain? One customer, the U.S. Chamber of Commerce, found out that criticizing the Postal Service can bring a deluge of mail from postmasters, with stamps paid for by unwitting postal customers.

And you can bet none of those letters were lost.

In April, the U.S. Chamber of Commerce sent its members a brochure that was critical of the Postal Service. It condemned a proposed postal rate increase and solicited "horror stories" about the Postal Service. The Postal Service pronounced the brochure full of distortions, and postmasters launched a counterattack.

On June 22, the mail began to roll in to the office of chamber president Richard Lesher. Within a week, Lesher's office was getting 100 letters a day, all from postmasters.

It looked like a legitimate grass-roots campaign -- postmasters from all over the country independently riled up by a personal insult. Except, they weren't from all over the country. Many of the letters were generated by copy machine, and postmasters used the franking privilege instead of buying their own stamps.

When chamber staff members looked closely, they found that all the mail came from the Postal Service's Central Region. Nearly all correspondence from Kansas was a form letter, and the majority of the letters were sent on Postal Service stationery stamped for official business.

The form letter said: "I am disappointed in the brochure and request that you publicly recall it. In addition, I request that you make a public apology to the United States Postal Service for the intentional harm and damage which you are endeavoring to perpetrate with such a publication."

Why did only the Central Region react to the chamber's brochure? On June 12, the regional postmaster general, Jerry K. Lee, wrote a letter to Lesher complaining about the brochure. Lee circulated a copy of his letter to his 14 division postmasters, who, in turn, sent a copy of the letter to all postmasters in the region.

Postal employees were not required to reply to the chamber, but hundreds of them had time on their hands to do so. And what with the stamps being free and quick delivery guaranteed, there was nothing to stand in their way.

James Mruk, spokesman for the Central Region, told our reporter Paul Zimmerman that the chamber's brochure was "a vicious attack on the world's best postal service. The attack from Mr. Lesher hurt {Lee}. Many of the employees were hurt as well. It was a response from the heart."

Mruk said the Postal Service has "a responsibility to respond to such attacks." He added: "We're not apologizing in any way for using official business stationery. We did it the most efficient and least expensive way we could." Least expensive for whom?

The independent Postal Rate Commission will decide by the beginning of the year whether the Postal Service's proposed rate increase is justified. A first-class stamp would go from 25 to 30 cents, the cost of sending postcards from 15 to 20 cents, and the cost of sending a 7-pound package from $4 to $5.06.