schedule_message · TrekMail MCP Server MCP: Risk & Policy

WHAT IT DOES

What schedule_message does on TrekMail MCP Server

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

WHY IT NEEDS A POLICY

Why schedule_message needs a policy

This tool creates a new scheduled message resource, which is a reversible write operation (the scheduled message can be cancelled or modified before send time). It is not Execute because scheduling is not code execution or triggering an external operation in real-time—the actual send happens later. It is not Financial or Destructive.

From the tool's definition Tool description states it 'Schedule[s] an email to be sent at a future date/time', which creates/modifies a message object in the system for deferred delivery.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

schedule_message Rate-limited

schedule_message 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": {
    "schedule_message": {
      "limits": [
        {
          "counter": "schedule_message_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 TrekMail MCP Server, so you can run agents against it safely.

FAQ

Questions about schedule_message

What does the schedule_message tool do? +

Schedule an email to be sent at a future date/time. Requires TREKMAIL_ALLOW_SENDING=true and confirm_send=true. It is categorised as a Write tool in the TrekMail MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on schedule_message? +

Register the TrekMail MCP Server MCP server in PolicyLayer and add a rule for schedule_message: 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 TrekMail MCP Server. Nothing to install.

What risk level is schedule_message? +

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

Can I rate-limit schedule_message? +

Yes. Add a rate_limit block to the schedule_message 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 schedule_message completely? +

Set action: deny in the PolicyLayer policy for schedule_message. 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 schedule_message? +

schedule_message is provided by the TrekMail MCP Server MCP server (trekmail/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.