Inquiries are continuing to determine the nature of the substance found at the Alliance and Leicester office in Douglas, which led to a security operation in the town centre.
The office on Prospect Hill was evacuated and sealed off after an envelope containing white power was discovered on Friday morning.
It triggered a full turn out of the Island's emergency services and a section of the main road was closed for nearly two hours.
A criminal inquiry's been launched and specialist officers from Merseyside called in to analyse the substance.
Police say initial tests show there are no contaminaiton issues to either staff or the property.
Bed shortages at Noble's are 'no threat' to TT 2026
Updates planned to beneficial ownership framework
Commissioners say residents left in 'void' over plans for onshore windfarm
Charity ball in Douglas to support air ambulance and neonatal care
Former TT racer died from head injuries after crash