If you're writing letters to the jolly man at the North Pole this holiday season you likely won't get a response from Santa Claus or his helpers. The U.S. Postal Service is droppinga popular natinal program begun in 1954 in the small Alaska town of the North Pole. Volunteers have been opening and responding to thousands of letters addressed to Santa each year. Replies come with North Pole postmarks. But, last year, a postal worker in Maryland recognized an Operation Santa volunteer there as a registered sex offender. The postal worker interceded before the individual could answer a child's letter, but the Postal Service viewed the episode as a big enough scare to tighten rules in such programs nationwide.