mail_move_email · Pyfastmail MCP: Risk & Policy

WHAT IT DOES

What mail_move_email does on Pyfastmail

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

WHY IT NEEDS A POLICY

Why mail_move_email needs a policy

Moving emails between mailboxes is a reversible modification operation. It changes email metadata (mailbox assignment) but does not delete data or create financial obligations. While the blast radius includes potential misorganization or accidental moves of sensitive emails to unintended folders, the reversibility and lack of data loss make this Write rather than Destructive.

From the tool's definition Tool description states "Move one or more emails to a mailbox identified by name" — this modifies the location/state of email objects reversibly. The action can be undone by moving emails back to their original mailbox.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mail_move_email Rate-limited

mail_move_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": {
    "mail_move_email": {
      "limits": [
        {
          "counter": "mail_move_email_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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

FAQ

Questions about mail_move_email

What does the mail_move_email tool do? +

Move one or more emails to a mailbox identified by name. It is categorised as a Write tool in the Pyfastmail MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on mail_move_email? +

Register the Pyfastmail MCP server in PolicyLayer and add a rule for mail_move_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 Pyfastmail. Nothing to install.

What risk level is mail_move_email? +

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

Can I rate-limit mail_move_email? +

Yes. Add a rate_limit block to the mail_move_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 mail_move_email completely? +

Set action: deny in the PolicyLayer policy for mail_move_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 mail_move_email? +

mail_move_email is provided by the Pyfastmail MCP server (pjosols/pyfastmail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.