list_emails

THE RISK

Low Risk

Why list_emails needs a policy

This tool queries and retrieves email metadata without modifying, deleting, or executing any actions. It is purely informational, returning UIDs and metadata (size, flags, attachment status). While it accesses email data, the lack of modification capabilities and the read-only nature place it squarely in the Read category.

From the tool's definition Tool name 'list_emails' and description 'List recent emails from a Yahoo Mail folder. Returns UIDs (permanent identifiers) and enriched metadata including size, flags, and attachment status.' indicates a retrieval operation with no side effects.

Documented attack patterns abuse exactly the kind of access list_emails gives an agent:

POLICY

How to control list_emails

PolicyLayer is an MCP gateway — it sits between your AI agents and Yahoo Mail, and nothing reaches the server without passing your rules. This is the rule we recommend for list_emails:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "list_emails": {}
  }
}

list_emails is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register Yahoo Mail — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Yahoo Mail tools

Destructive delete_emails Move emails to Trash folder using UIDs (soft delete, recoverable). UIDs are permanent iden Write unflag_emails Remove flag/star from emails using UIDs. UIDs are permanent identifiers. Write flag_emails Flag emails as important/starred using UIDs. UIDs are permanent identifiers. Write archive_emails Move emails to Archive folder using UIDs for long-term storage. UIDs are permanent identif Write mark_as_read Mark emails as read using UIDs. UIDs are permanent identifiers. Write mark_as_unread Mark emails as unread using UIDs. UIDs are permanent identifiers. Write move_emails Move emails to a specified folder using UIDs. UIDs are permanent identifiers. Use list_fol Read list_folders List all available IMAP folders/mailboxes in your Yahoo Mail account

All 11 Yahoo Mail tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about list_emails

What does the list_emails tool do? +

List recent emails from a Yahoo Mail folder. Returns UIDs (permanent identifiers) and enriched metadata including size, flags, and attachment status. It is categorised as a Read tool in the Yahoo Mail MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on list_emails? +

Register the Yahoo Mail MCP server in PolicyLayer and add a rule for list_emails: 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 Yahoo Mail. Nothing to install.

What risk level is list_emails? +

list_emails is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit list_emails? +

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

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

list_emails is provided by the Yahoo Mail MCP server (jtokib/yahoo-mail-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Yahoo Mail tool call.

Start from Yahoo Mail, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →