Update mail/SMTP configuration for system email alerts. All fields are optional — only provide the ones you want to change.
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.
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.
Documented attack patterns abuse exactly the kind of access mail_update 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_update:
{
"version": "1",
"default": "deny",
"tools": {
"mail_update": {
"limits": [
{
"counter": "mail_update_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}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.
Free to start. No card required.
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.
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.
mail_update is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
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.
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.
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.
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.