There was no intentional delay at the U.S. Postal Service aimed at preventing a Hillary Clinton campaign mailing from reaching voters prior to Maine’s Democratic caucus, according to a spokesman for the Postal Service’s Office of Inspector General.

The spokesman, Dan Mihalko, said the case remains under investigation, and postal agents have not determined why the mass mailing did not reach voters prior to the Feb. 10 caucus. But he said the investigation has ruled out the possibility that there was an intentional delay.

The Clinton campaign mailing was meant to remind voters of the Democratic presidential caucuses, which were won by Barack Obama. The mail was processed at the Postal Service’s distribution center in Scarborough.