reply_all_email · Microsoft MCP: Risk & Policy

WHAT IT DOES

What reply_all_email does on Microsoft MCP

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

WHY IT NEEDS A POLICY

Why reply_all_email needs a policy

This tool sends a reply to all recipients of an email, which is a write operation creating new email messages. The severity is high because an AI agent could inadvertently send replies to large groups of recipients, potentially exposing sensitive information or causing reputational harm at scale.

From the tool's definition Reply to all recipients of an email

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

reply_all_email Rate-limited

reply_all_email 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": {
    "reply_all_email": {
      "limits": [
        {
          "counter": "reply_all_email_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

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

FAQ

Questions about reply_all_email

What does the reply_all_email tool do? +

Reply to all recipients of an email. It is categorised as a Write tool in the Microsoft MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on reply_all_email? +

Register the Microsoft MCP server in PolicyLayer and add a rule for reply_all_email: 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 Microsoft MCP. Nothing to install.

What risk level is reply_all_email? +

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

Can I rate-limit reply_all_email? +

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

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

reply_all_email is provided by the Microsoft MCP server (purva-kashyap/microsoft-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.