AI agents use add-smtp-config to create or update resources in SMTP MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your SMTP MCP Server environment.
This tool creates new SMTP configurations, which is a reversible data creation operation (Write category). Severity is high because misconfigured or malicious SMTP credentials could enable unauthorized bulk email sending, spam campaigns, or phishing attacks through the sibling tools (send-email, send-bulk-emails).
From the tool's definition Tool name 'add-smtp-config' and description 'Add a new SMTP configuration' indicate creation of new SMTP configuration data.
Documented attack patterns abuse exactly the kind of access add-smtp-config gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and SMTP MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for add-smtp-config:
{
"version": "1",
"default": "deny",
"tools": {
"add-smtp-config": {
"limits": [
{
"counter": "add-smtp-config_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add-smtp-config 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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Add a new SMTP configuration. It is categorised as a Write tool in the SMTP MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the SMTP MCP Server MCP server in PolicyLayer and add a rule for add-smtp-config: 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 SMTP MCP Server. Nothing to install.
add-smtp-config 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 add-smtp-config 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 add-smtp-config. 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.
add-smtp-config is provided by the SMTP MCP Server MCP server (samihalawa/mcp-server-smtp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from SMTP 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.
11 SMTP MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.