Investigations are under way by police in Northamptonshire after an envelope containing white powder was received at the offices of the DVLA.
The envelope was isolated in the post room and removed for tests
The contents of the envelope have been found by officers to be harmless.
At this stage police are not linking this episode at the Northampton offices with other incidents involving devices being sent through the post.
Four people came into contact with the powder on Friday but none suffered any ill effects.
The envelope was isolated in the post room and the building was not evacuated, with business carrying on as normal.
The envelope was later removed by specially trained police officers working with fire officers.
The substance was found to be harmless.
Superintendent Bob Smart, who commanded the incident, said: "While we don't believe there is a link with any other incidents, we are keeping an open mind and it will be fully investigated."