mail_add_rule · Mailgent MCP Server MCP: Risk & Policy

WHAT IT DOES

What mail_add_rule does on Mailgent MCP Server

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

WHY IT NEEDS A POLICY

Why mail_add_rule needs a policy

This tool creates new email rules, which is a write operation that modifies email handling configuration. It is not destructive (rules can be changed or removed), not financial, and not execute-level (it does not run arbitrary code or trigger external operations based on user input).

From the tool's definition Tool description states 'Add an allow or block rule' — this creates or modifies email filtering rules that are applied going forward. The rules affect email handling behavior (RECEIVE/SEND/REPLY scopes) but are reversible via deletion or modification of rules.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mail_add_rule Rate-limited

mail_add_rule 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_add_rule": {
      "limits": [
        {
          "counter": "mail_add_rule_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 Mailgent MCP Server, so you can run agents against it safely.

FAQ

Questions about mail_add_rule

What does the mail_add_rule tool do? +

Add an allow or block rule for email. Use type ALLOW or BLOCK, scope RECEIVE/SEND/REPLY, and value as email or *@domain.com pattern. It is categorised as a Write tool in the Mailgent 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 mail_add_rule? +

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

What risk level is mail_add_rule? +

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

Can I rate-limit mail_add_rule? +

Yes. Add a rate_limit block to the mail_add_rule 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_add_rule completely? +

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

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