Send a test email to verify mail configuration is working. Provide a subject, body text, and one or more recipient addresses.
AI agents invoke mail_send to trigger actions in Truenas. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
This tool triggers an external operation (sending an email) whose effects depend on arguments (subject, body, recipients). It does not simply read or write data within the system—it causes an external side effect by delivering email to specified recipients. Misuse could lead to spam or phishing emails being sent to arbitrary addresses.
From the tool's definition Send a test email to verify mail configuration is working. Provide a subject, body text, and one or more recipient addresses.
Documented attack patterns abuse exactly the kind of access mail_send gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Truenas, and nothing reaches the server without passing your rules. This is the rule we recommend for mail_send:
{
"version": "1",
"default": "deny",
"tools": {
"mail_send": {
"limits": [
{
"counter": "mail_send_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}mail_send stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Send a test email to verify mail configuration is working. Provide a subject, body text, and one or more recipient addresses. It is categorised as a Execute tool in the Truenas MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Truenas MCP server in PolicyLayer and add a rule for mail_send: 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.
mail_send is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the mail_send 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.
Set action: deny in the PolicyLayer policy for mail_send. 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.
mail_send 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.
Start from Truenas, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
279 Truenas tools catalogued and risk-classified — across an index of 43,000+ MCP servers.