add_sending_domain · Campaign Monitor MCP: Risk & Policy

WHAT IT DOES

What add_sending_domain does on Campaign Monitor MCP

AI agents use add_sending_domain to create or update resources in Campaign Monitor MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Campaign Monitor MCP environment.

WHY IT NEEDS A POLICY

Why add_sending_domain needs a policy

This tool creates/adds a new sending domain configuration, which is a write operation that modifies client account settings. While it affects email delivery infrastructure, it is reversible and does not destroy data or execute arbitrary code.

From the tool's definition The tool name 'add_sending_domain' and description 'Add a sending domain for a client' indicates creation of a new resource (sending domain configuration). This is a reversible modification operation—domains can be removed or reconfigured if needed.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_sending_domain Rate-limited

add_sending_domain stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "add_sending_domain": {
      "limits": [
        {
          "counter": "add_sending_domain_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Campaign Monitor MCP, so you can run agents against it safely.

FAQ

Questions about add_sending_domain

What does the add_sending_domain tool do? +

Add a sending domain for a client. It is categorised as a Write tool in the Campaign Monitor MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_sending_domain? +

Register the Campaign Monitor MCP server in PolicyLayer and add a rule for add_sending_domain: 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 Campaign Monitor MCP. Nothing to install.

What risk level is add_sending_domain? +

add_sending_domain is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit add_sending_domain? +

Yes. Add a rate_limit block to the add_sending_domain 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.

How do I block add_sending_domain completely? +

Set action: deny in the PolicyLayer policy for add_sending_domain. 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.

What MCP server provides add_sending_domain? +

add_sending_domain is provided by the Campaign Monitor MCP server (pauliowest/cmon-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.