The 56-year-old postal carrier stockpiled hundreds of pieces of undelivered mail in lockers and empty mailboxes along his route in Elkhart County, authorities said.
Graybill has been charged with obstruction of mail, unlawful delay of mail by a postal employee and embezzlement of mail by a postal employee in a three-count federal grand jury indictment.
Graybill has pleaded not guilty and will go to trial in October. His attorney, H. Jay Stevens, has not responded to request for comment.
In April, postal inspectors found more than 1,000 pieces of mail in lockers at a mobile home park in Elkhart, according to the South Bend Tribune
Graybill meant to process all the mail intended for addresses that were vacant, authorities said. The postmarks ranged from December 2007 through April 2009.
Much of the mail was first-class, said Mary Hatton, spokeswoman for David Capp, U.S. attorney for the northern district of Indiana. Graybill was charged after a U.S. Postal Inspection Service investigation.