mail_rename_mailbox · Pyfastmail MCP: Risk & Policy

WHAT IT DOES

What mail_rename_mailbox does on Pyfastmail

AI agents use mail_rename_mailbox 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_rename_mailbox needs a policy

This tool performs a reversible modification operation (renaming) on email account structure. It is a Write operation because it changes data state but remains undoable—the mailbox can be renamed back to its original name. Severity is medium because misuse could cause organizational confusion or disruption to the email account structure, but does not result in data loss or financial impact.

From the tool's definition Tool name is 'mail_rename_mailbox' and description states 'Rename a mailbox (folder or label) by its ID.' The action of renaming modifies metadata associated with a mailbox but does not delete data or cause irreversible changes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mail_rename_mailbox Rate-limited

mail_rename_mailbox 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_rename_mailbox": {
      "limits": [
        {
          "counter": "mail_rename_mailbox_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 Pyfastmail, so you can run agents against it safely.

FAQ

Questions about mail_rename_mailbox

What does the mail_rename_mailbox tool do? +

Rename a mailbox (folder or label) by its ID. 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_rename_mailbox? +

Register the Pyfastmail MCP server in PolicyLayer and add a rule for mail_rename_mailbox: 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_rename_mailbox? +

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

Can I rate-limit mail_rename_mailbox? +

Yes. Add a rate_limit block to the mail_rename_mailbox 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_rename_mailbox completely? +

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

mail_rename_mailbox 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.