Compose and send a new email to one or more recipients. Requires a paid plan (Standard or Plus). Rate limits vary by plan (Standard: 30/hr, 200/day; Plus: 60/hr, 500/day).
Part of the PO6 Mailbox server.
Free to start. No card required.
AI agents use compose_email to create or modify resources in PO6 Mailbox. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call compose_email repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach PO6 Mailbox.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"compose_email": {
"limits": [
{
"counter": "compose_email_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full PO6 Mailbox policy for all 39 tools.
These attack patterns abuse exactly the kind of access compose_email gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Compose and send a new email to one or more recipients. Requires a paid plan (Standard or Plus). Rate limits vary by plan (Standard: 30/hr, 200/day; Plus: 60/hr, 500/day).. It is categorised as a Write tool in the PO6 Mailbox MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the PO6 Mailbox MCP server in PolicyLayer and add a rule for compose_email: 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 PO6 Mailbox. Nothing to install.
compose_email 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 compose_email 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 compose_email. 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.
compose_email is provided by the PO6 Mailbox MCP server (https://mcp.po6.com). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 39 PO6 Mailbox tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.