New Forest DC, Eastleigh BC and Test Valley BC received harmless white powder and Winchester City Council found white powder in its car park on Thursday.
On police advice, council press officers were being deliberately vague in order to minimise publicity and discourage further hoaxes.
A Hampshire CC spokeswoman said: 'We had an envelope delivered. The police took it away for examination. Normal business at the county council resumed straight away.'
A Hampshire police spokeswoman said the substance was harmless, and not linked to a terrorist attack.