sendEmail · Postmark MCP Server MCP: Risk & Policy

WHAT IT DOES

What sendEmail does on Postmark MCP Server

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

WHY IT NEEDS A POLICY

Why sendEmail needs a policy

Sending email is a write operation that creates new data (email messages) in an external system with reversible side effects. It is not destructive (emails can be unsent or recalled in some systems), not financial, and not arbitrary code execution.

From the tool's definition Tool name 'sendEmail' combined with server description stating the server 'Enables sending and managing emails via Postmark' indicates this tool creates and sends email messages.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

sendEmail Rate-limited

sendEmail 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": {
    "sendEmail": {
      "limits": [
        {
          "counter": "sendemail_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 Postmark MCP Server, so you can run agents against it safely.

FAQ

Questions about sendEmail

What does the sendEmail tool do? +

sendEmail. It is categorised as a Write tool in the Postmark 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 sendEmail? +

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

What risk level is sendEmail? +

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

Can I rate-limit sendEmail? +

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

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

sendEmail is provided by the Postmark MCP Server MCP server (lupiita4/postmark-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.