Purpose: Send (or schedule) an existing broadcast by ID. The broadcast must have been created with create-broadcast first. NOT for: Sending a new one-off email (use send-email). Not for creating the broadcast content (use create-broadcast). Returns: Send confirmation and broadcast ID. When to use...
AI agents invoke send-broadcast to trigger actions in Email Sending MCP. 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.
Sending a broadcast triggers an external operation (mass email delivery) that cannot be fully undone once dispatched. While cancel-email exists as a sibling tool suggesting some cancellation is possible, the act of sending to a broadcast list is an irreversible external operation with high blast radius if misused (e.g., sending to wrong audience or with wrong content).
From the tool's definition "Send (or schedule) an existing broadcast" and "Send confirmation and broadcast ID" — triggers delivery of an email broadcast to potentially large recipient lists
Documented attack patterns abuse exactly the kind of access send-broadcast 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 send-broadcast:
{
"version": "1",
"default": "deny",
"tools": {
"send-broadcast": {
"limits": [
{
"counter": "send-broadcast_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}send-broadcast 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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Purpose: Send (or schedule) an existing broadcast by ID. The broadcast must have been created with create-broadcast first. NOT for: Sending a new one-off email (use send-email). Not for creating the broadcast content (use create-broadcast). Returns: Send confirmation and broadcast ID. When to use: - User has created a broadcast and says. It is categorised as a Execute tool in the Email Sending MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Email Sending MCP server in PolicyLayer and add a rule for send-broadcast: 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.
send-broadcast 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 send-broadcast 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 send-broadcast. 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.
send-broadcast 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.