Cancel a scheduled email before it is sent.
AI agents call cancel_email to permanently remove resources in Unosend MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Cancelling a scheduled email is an irreversible action — once cancelled, the scheduled send cannot be undone or recovered. This makes it Destructive rather than Write. The blast radius is medium: an AI agent misusing this tool could cancel legitimate scheduled email campaigns, causing business disruption, but it does not affect financial transactions or delete persistent data.
From the tool's definition Cancel a scheduled email before it is sent
Attacks that exploit this kind of access
Cancel a scheduled email before it is sent. It is categorised as a Destructive tool in the Unosend MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Unosend MCP Server MCP server in PolicyLayer and add a rule for cancel_email: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Unosend MCP Server. Nothing to install.
cancel_email is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the cancel_email rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for cancel_email. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
cancel_email is provided by the Unosend MCP Server MCP server (unosend/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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