sendHtmlEmail · MCP Email Server MCP: Risk & Policy

WHAT IT DOES

What sendHtmlEmail does on MCP Email Server

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

WHY IT NEEDS A POLICY

Why sendHtmlEmail needs a policy

This tool creates and sends new email messages, which is a reversible write operation. While email cannot be unsent once delivered, the tool itself performs a create/send action rather than deletion.

From the tool's definition Tool name is 'sendHtmlEmail' and description states 'Send an HTML email' with attachments capability. The verb 'Send' indicates creation and transmission of email messages.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

sendHtmlEmail Rate-limited

sendHtmlEmail 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": {
    "sendHtmlEmail": {
      "limits": [
        {
          "counter": "sendhtmlemail_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 MCP Email Server, so you can run agents against it safely.

FAQ

Questions about sendHtmlEmail

What does the sendHtmlEmail tool do? +

Send an HTML email. Attachments: list of local file paths like [. It is categorised as a Write tool in the MCP Email 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 sendHtmlEmail? +

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

What risk level is sendHtmlEmail? +

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

Can I rate-limit sendHtmlEmail? +

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

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

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