Twenty-one-year-old Willie Buck Jones admitting to throwing mail in a dumpster on two occasions in January.
He faces up to 10 years in prison and a $500,000 fine.
In the meantime there has been a not guilty plea from another former letter carrier.
Twenty-two-year veteran Darrell Gallagher will face charges he threw away "address cards and circulars" in November. His trial is set for April 16.