AI agents use send-serial-email to create or update resources in Apple Mail — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Apple Mail environment.
Sending emails is a reversible write operation—messages can be deleted or unsent depending on mail server support, and the primary effect is creating/transmitting data. While potentially misused for spam or impersonation, the category is Write rather than Execute (which would apply to arbitrary code execution) or Destructive (which would require irreversible deletion).
From the tool's definition Tool name 'send-serial-email' combined with server description stating it 'allows AI assistants to...send...emails in Apple Mail.' The tool sends email messages, which creates new data (outbound communications) with external recipients.
Documented attack patterns abuse exactly the kind of access send-serial-email gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Apple Mail, and nothing reaches the server without passing your rules. This is the rule we recommend for send-serial-email:
{
"version": "1",
"default": "deny",
"tools": {
"send-serial-email": {
"limits": [
{
"counter": "send-serial-email_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send-serial-email 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.
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send-serial-email. It is categorised as a Write tool in the Apple Mail MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Apple Mail MCP server in PolicyLayer and add a rule for send-serial-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 Apple Mail. Nothing to install.
send-serial-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 send-serial-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 send-serial-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.
send-serial-email is provided by the Apple Mail MCP server (sweetrb/apple-mail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 40 Apple Mail tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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40 Apple Mail tools catalogued and risk-classified — across an index of 42,500+ MCP servers.