update_email · Eml MCP: Risk & Policy

WHAT IT DOES

What update_email does on Eml

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

WHY IT NEEDS A POLICY

Why update_email needs a policy

The tool modifies (write operation) an existing email draft rather than deleting it (Destructive) or executing arbitrary code (Execute). The modification is reversible and limited to draft emails. Severity is medium because email modifications can cause confusion or unwanted message changes, but the impact is constrained to drafts and the operation is reversible.

From the tool's definition Tool description states 'Modify an existing .eml draft and re-open it', and the server manages email archives with drafts that can be written to.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_email Rate-limited

update_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": {
    "update_email": {
      "limits": [
        {
          "counter": "update_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 Eml, so you can run agents against it safely.

FAQ

Questions about update_email

What does the update_email tool do? +

Modify an existing .eml draft and re-open it. It is categorised as a Write tool in the Eml MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_email? +

Register the Eml MCP server in PolicyLayer and add a rule for update_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 Eml. Nothing to install.

What risk level is update_email? +

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

Can I rate-limit update_email? +

Yes. Add a rate_limit block to the update_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 update_email completely? +

Set action: deny in the PolicyLayer policy for update_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 update_email? +

update_email is provided by the Eml MCP server (miguelripoll23/eml-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.