“I don’t know what they’re talking about,” Mr. Saint-Albord told reporters upon leaving the courtroom, referring to the charges. He and Ms. Strickland were released on $50,000 bond. Mr. Jackson was released on his own recognizance. None of the defendants’ lawyers would comment on the charges.

The scheme played out in the post office on Eighth Avenue. As part of Operation Santa, which began in 1912, workers receive hundreds of thousands of letters from children to Santa. Some of the letters are then placed in a public “adoption” area for donors, with the children’s identities and addresses redacted. When the donor returns to the post office with the gift, workers put it in the mail to the lucky child. Of the more than 300,000 letters received during the 2013 holiday season, the complaint says, just a few thousand were ultimately fulfilled.

The complaint, prepared by a special agent with the Postal Service Office of Inspector General and filed this month, says the workers wrote letters on behalf of family members or fictional children, and then made copies of them to raise the chances they were chosen by a Secret Santa.

The letters received a further lift when Ms. Strickland, who worked in the “adoption” area, arranged them prominently among the display for donors. She would let her colleagues know when one of their letters had been chosen.

Mr. Jackson admitted in an interview with an agent in February that he had written four or five letters pretending to be a child, the complaint says. For his efforts, a printer, two laptop computers, two tablets, clothing, bedding and gift cards arrived at his home — like a less poetic version of the Grinch’s thievery.