You’ve not provided enough information. What is the cause of these emails being sent, and what kind of threat is involved? And who is the resident – owner, tenant on strata roll, or someone else?
Assuming this involves a strata problem, the initial response would be to tell the resident to correspond with the strata manager (who would have been delegated the secretary’s tasks, including dealing with correspondence from owners and tenants on the strata roll). At some point this issue should be considered at a strata committee meeting. Everyone should remember that the strata committee secretary has a limited decision making ability – all decisions apart from a couple of mundane ones like calling meetings, are made by the committee as a whole, with an agenda motion, and the minuted decision available to all owners, with the reasoning for the decision provided. The decision should be reasonable and fair, or else NCAT can be called in to review and reconsider the situation.
A further option, that may de-escalate the situation is to refer the resident to NCAT and to make a formal complaint there, and encourage an NCAT mediation session. The NCAT mediations (whatever their other problems) act as a neutral party, and will determine the facts and will explain the law to all the parties involved.