start_migration · TrekMail MCP Server MCP: Risk & Policy

WHAT IT DOES

What start_migration does on TrekMail MCP Server

AI agents invoke start_migration to trigger actions in TrekMail MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why start_migration needs a policy

This tool triggers a complex, multi-step external operation (IMAP migration) whose outcomes depend on provided arguments and cannot be trivially reversed mid-execution. While not immediately destructive or financial, it executes code/operations against external systems and infrastructure.

From the tool's definition Tool description states 'Start migrating emails from a source IMAP server to a TrekMail mailbox' and explicitly notes 'This is a long-running operation' with required confirmation flags (TREKMAIL_ALLOW_MIGRATION=true and confirm_start=true).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

start_migration Rate-limited

start_migration stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "start_migration": {
      "limits": [
        {
          "counter": "start_migration_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about start_migration

What does the start_migration tool do? +

Start migrating emails from a source IMAP server to a TrekMail mailbox. This is a long-running operation. Both TREKMAIL_ALLOW_MIGRATION=true and confirm_start=true are required. It is categorised as a Execute tool in the TrekMail MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on start_migration? +

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

What risk level is start_migration? +

start_migration is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit start_migration? +

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

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

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