A package containing white powder found at the postal sorting office at Mallusk, Co Antrim was found to be harmless.
Police and the Northern Ireland Fire and Rescue service attended the scene following the discovery at Enterprise Way at around 10:30am this morning.
A spokesperson for the Royal Mail confirmed that white powder had been found in an item at the sorting centre.
The incident had not hampered the mail centre operations.
The powder was checked by Northern Ireland Fire and Rescue Service and found to be a non-hazardous substance.
A Royal Mail spokesperson said this morning: “The safety of our people is of the utmost priority and in line with our policy and procedures, the emergency services attended and the area where the powder was found was cordoned off.
“We are assisting the emergency services with their investigation. There is no impact on the operation of the mail centre and the processing of mail.”