Send an existing draft email. The draft must have recipients (to/cc/bcc) and a from address. After sending, the email is moved to the Sent folder and the draft keyword is removed.
AI agents use send_draft to create or update resources in Fastmail MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Fastmail MCP Server environment.
This is a Write operation because it creates an outbound email message with side effects (moving to Sent, removing draft status). While emails cannot be easily unsent, the primary action is creating/committing the message rather than permanent deletion.
From the tool's definition Tool description states 'Send an existing draft email' which modifies email state by moving it from Drafts to Sent folder and removing the draft keyword. The tool commits and delivers a message to recipients.
Documented attack patterns abuse exactly the kind of access send_draft gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Fastmail MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for send_draft:
{
"version": "1",
"default": "deny",
"tools": {
"send_draft": {
"limits": [
{
"counter": "send_draft_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send_draft 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 an existing draft email. The draft must have recipients (to/cc/bcc) and a from address. After sending, the email is moved to the Sent folder and the draft keyword is removed. It is categorised as a Write tool in the Fastmail MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Fastmail MCP Server MCP server in PolicyLayer and add a rule for send_draft: 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 Fastmail MCP Server. Nothing to install.
send_draft 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_draft 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_draft. 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_draft is provided by the Fastmail MCP Server MCP server (madllama25/fastmail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Fastmail MCP Server, 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.
38 Fastmail MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.