Validate an email address: syntax (RFC 5322), typo correction (gnail→gmail), classification (disposable, role, free provider), MX lookup, and live SMTP mailbox probe. Returns an aggregated
AI agents call postio_email_validate to retrieve information from Postio without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs validation and verification checks on email addresses. It queries external systems (DNS, SMTP servers) and performs local syntax analysis, but does not create, modify, delete, or execute arbitrary operations. The 'live SMTP mailbox probe' is a read-only verification check that does not send mail or alter mailbox state. The aggregated return is informational only.
From the tool's definition Tool description states it 'Validate[s] an email address' with operations including 'syntax', 'typo correction', 'classification', 'MX lookup', and 'live SMTP mailbox probe'.
Attacks that exploit this kind of access
Validate an email address: syntax (RFC 5322), typo correction (gnail→gmail), classification (disposable, role, free provider), MX lookup, and live SMTP mailbox probe. Returns an aggregated. It is categorised as a Read tool in the Postio MCP Server, which means it retrieves data without modifying state.
Register the Postio MCP server in PolicyLayer and add a rule for postio_email_validate: 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 Postio. Nothing to install.
postio_email_validate is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the postio_email_validate 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 postio_email_validate. 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.
postio_email_validate is provided by the Postio MCP server (postio-uk/postio-integrations). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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