mail_update

Update mail/SMTP configuration for system email alerts. All fields are optional — only provide the ones you want to change.

SERVERTruenas SOURCEspranab/truenas-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/spranab-truenas-mcp/mail-update.md

WHAT IT DOES

What mail_update does on Truenas

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

RISK

Why mail_update is rated Medium

This tool creates or modifies SMTP/mail configuration settings reversibly. While it affects system behavior (email alert delivery), the changes are not destructive and can be reverted by updating the configuration again. The severity is medium because misconfiguration could disrupt critical system notifications, but no data is deleted and no external financial transactions are involved.

From the tool's definition Tool name 'mail_update' and description explicitly states 'Update mail/SMTP configuration' — this modifies system email settings.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs mail_update safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Truenas, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For mail_update, this is the rule to start with:

mail_update Rate-limited

mail_update 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_update": {
      "limits": [
        {
          "counter": "mail_update_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Truenas, apply this rule, and every mail_update call is checked against it from then on.

FAQ

Questions about mail_update

What does the mail_update tool do? +

Update mail/SMTP configuration for system email alerts. All fields are optional — only provide the ones you want to change. It is categorised as a Write tool in the Truenas 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_update? +

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

What risk level is mail_update? +

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

Can I rate-limit mail_update? +

Yes. Add a rate_limit block to the mail_update 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_update completely? +

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

mail_update is provided by the Truenas MCP server (spranab/truenas-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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