mail_reply · Mailgent MCP Server MCP: Risk & Policy

WHAT IT DOES

What mail_reply does on Mailgent MCP Server

AI agents use mail_reply 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_reply needs a policy

Sending a reply to an email is a Write operation — it creates a new message in an existing thread and delivers it externally. It is reversible only in the sense that the message is sent (it cannot be unsent, but no data is deleted). The blast radius is high because a misused agent could send replies impersonating the user to arbitrary recipients, leaking sensitive information or causing reputational/business harm.

From the tool's definition Reply to an existing email in a thread

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mail_reply Rate-limited

mail_reply 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_reply": {
      "limits": [
        {
          "counter": "mail_reply_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_reply

What does the mail_reply tool do? +

Reply to an existing email in a thread. 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_reply? +

Register the Mailgent MCP Server MCP server in PolicyLayer and add a rule for mail_reply: 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_reply? +

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

Can I rate-limit mail_reply? +

Yes. Add a rate_limit block to the mail_reply 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_reply completely? +

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

mail_reply 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.