A sex offender has taken some of the joy out of the Postal Service's Operation Santa program.

For decades, many children's letters to Santa have been answered by volunteers walking into post offices around the country and responding to kids' wishes. Most sent gifts, or even delivered them in person.

But those face-to-face encounters are over after a sex offender was spotted among the volunteers this week, leading to a brief suspension of the program.

Operation Santa resumed on Saturday in New York and Chicago. But now, postal workers are blocking out any personal information from "Dear Santa" letters and substituting codes that match addresses known only to the post office. Only then are gifts mailed.

A post office spokesman says the spirit of giving is still there, but times change.