update_domain_signature · TrekMail MCP Server MCP

WHAT IT DOES

What update_domain_signature does on TrekMail MCP Server

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

WHY IT NEEDS A POLICY

Why update_domain_signature needs a policy

This tool modifies domain-level email signature settings, which affects email presentation but does not delete data (Destructive), execute arbitrary code (Execute), create financial obligations (Financial), or retrieve data without side effects (Read). It is a reversible configuration change (can be toggled off or changed), making it Write.

From the tool's definition Tool description states it "Set[s] the per-domain email signature" with modes including 'off', 'default', and 'enforced', and accepts HTML input. The verbs 'set' and 'enforced' indicate modification of configuration data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_domain_signature Rate-limited

update_domain_signature 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_domain_signature": {
      "limits": [
        {
          "counter": "update_domain_signature_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 TrekMail MCP Server, so you can run agents against it safely.

FAQ

Questions about update_domain_signature

What does the update_domain_signature tool do? +

Set the per-domain email signature. mode=off disables; mode=default seeds newly-created mailbox identities; mode=enforced overrides per-mailbox signatures on the webmail compose path. signature_html accepts safe HTML (up to 10000 chars); unsafe tags are stripped. It is categorised as a Write tool in the TrekMail MCP Server 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_domain_signature? +

Register the TrekMail MCP Server MCP server in PolicyLayer and add a rule for update_domain_signature: 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 update_domain_signature? +

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

Can I rate-limit update_domain_signature? +

Yes. Add a rate_limit block to the update_domain_signature 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_domain_signature completely? +

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

update_domain_signature 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.