Update an existing domain in Resend. Allows changing tracking settings, TLS mode, and capabilities.
AI agents use update-domain to create or update resources in Email Sending MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Email Sending MCP environment.
This tool modifies domain settings in Resend (a transactional email service), which constitutes Write operations. While domain misconfigurations could have downstream consequences for email delivery, the tool itself performs reversible updates rather than executing arbitrary code or destructively removing resources.
From the tool's definition The tool description states it 'Allows changing tracking settings, TLS mode, and capabilities' on an existing domain. These are modifications to domain configuration that are reversible and do not delete data or move money.
Documented attack patterns abuse exactly the kind of access update-domain gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Email Sending MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for update-domain:
{
"version": "1",
"default": "deny",
"tools": {
"update-domain": {
"limits": [
{
"counter": "update-domain_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}update-domain 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 an existing domain in Resend. Allows changing tracking settings, TLS mode, and capabilities. It is categorised as a Write tool in the Email Sending MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Email Sending MCP server in PolicyLayer and add a rule for update-domain: 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 Email Sending MCP. Nothing to install.
update-domain 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 update-domain 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 update-domain. 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.
update-domain is provided by the Email Sending MCP server (resend/resend-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 77 Email Sending MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
77 Email Sending MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.