HAGERSTOWN, Md. — A utility company's shipment of compact fluorescent light bulbs to its 220,000 Maryland customers caused headaches for small-town postal workers who had to deal with thousands of unexpected packages during the peak holiday season.

Allegheny Power sent the two-bulb parcels to its western Maryland customers to promote energy efficiency.

Spokesman Todd Meyers said Monday that the bulbs were supposed to arrive by late November, but a supplier glitch, combined with the company's ignorance about the workings of some post offices, generated resentment.

Managers said they had to pay workers overtime to unpack large cartons filled with boxes of bulbs.

"They came in waves," said Jay Jones, customer service supervisor at the post office in Hagerstown, population 39,000.