Thames-Coromandel District mayor Len Salt used the frank sign-off in an email last year in the hope of ending correspondence.

“Please keep a record of my reply in case you need to refer to it for legal reasons or future court cases,” he wrote.

“My official response, as Mayor of Thames-Coromandel District Council, to your request for personal details of staff names and addresses, is this.

“Go f*** yourself.

“Kind regards, Len.”

The original email to Mr Salt accuses him and his council of “extremely unlawful actions”, of acting as a “fictitious entity” with “intent to coerce to deceive to enslave myself and others”.

Mr Salt told AAP the same individual had been harassing councillors and staff for years, with a report in NZ media outlet Stuff saying he was operating under the guise of the sovereign citizen movement.

Sovereign citizens believe they are not subject to laws and regulations created by governments, or rulings made by courts.

Mr Salt said he took the request for private information of staff members as a sign of an escalating threat.

The mayor gave it short shrift as he said he had a low tolerance for abusive or harassing dealings, which have risen dramatically in recent years.

“This is happening on multiple levels. Social media, emails, face-to-face contact across customer service counters, in council meetings and community board meetings, in public information sessions organised by council staff, in the streets and supermarkets,” he said.

Mr Salt told Stuff local authorities had taken various security measures in recent years, calling police and providing panic alarms to councillors.

“I was shocked to see even places like the local (conservation) office having bullet-proof glass inserted,” Mr Salt said.

After the publication of the email chain this week – first made public by a political rival of Mr Salt posted on social media – Mr Salt said most backed his bluntness.

“I’ve had a huge amount of positive response including from many mayors and elected members, past and present, as well as residents and ratepayers from across the country,” he told AAP.

“The real issue is not that one mayor dropped an F-Bomb, but the amount of aggression that council staff and elected members are subjected to on a daily basis.

“So, let’s move the discussion on to how we can counter that behaviour and build stronger, kinder, more tolerant and more collaborative communities.

“I’ll promise to stop swearing if we can all make that happen.”