forward_email · Email MCP: Risk & Policy

WHAT IT DOES

What forward_email does on Email

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

WHY IT NEEDS A POLICY

Why forward_email needs a policy

Forwarding an email sends a new message to external recipients, which is a write/send operation with significant blast radius — it can exfiltrate sensitive email content and attachments to arbitrary third parties. It is reversible in the sense that the email is not deleted, but the outbound send itself cannot be recalled, making it high severity.

From the tool's definition Forward an email. Preserves the original subject (FW:), quoted body, and attachments.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

forward_email Rate-limited

forward_email 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": {
    "forward_email": {
      "limits": [
        {
          "counter": "forward_email_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 Email, so you can run agents against it safely.

FAQ

Questions about forward_email

What does the forward_email tool do? +

Forward an email. Preserves the original subject (FW:), quoted body, and attachments. The. It is categorised as a Write tool in the Email MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on forward_email? +

Register the Email MCP server in PolicyLayer and add a rule for forward_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 Email. Nothing to install.

What risk level is forward_email? +

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

Can I rate-limit forward_email? +

Yes. Add a rate_limit block to the forward_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.

How do I block forward_email completely? +

Set action: deny in the PolicyLayer policy for forward_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.

What MCP server provides forward_email? +

forward_email is provided by the Email MCP server (kerodkibatu/email-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.