SMTP Email Check — Validate Addresses & Deliverability
Check an email address, its domain’s MX records, and SMTP deliverability before you send.
Validate email addresses and their underlying infrastructure before a campaign, signup form, or lead list. The tool checks the domain’s MX records, attempts an SMTP-level ping, and returns a verdict plus server greeting. Free 5 checks per day per IP, no signup.
Daily free limit reached
You've used your 5 free uses today. Continue pay-per-use via the DeFi Intel Agent Gateway API, or add a prepaid API key above for unlimited use.
Use this at scale or in your own tools
The same engine powers the DeFi Intel Agent Gateway: 40+ paid microservices on USDC (Base), no API keys required for pay-per-call, MCP transport for AI agents. Free samples daily.
Frequently asked questions
Is the SMTP email check free?
Yes — 5 free checks per day per IP, no signup. After the limit, continue via the DeFi Intel Agent Gateway API (pay-per-use) or a prepaid API key.
What does it check?
It resolves the domain, lists its MX records, attempts an SMTP connection and reports a verdict — e.g. connected, connection failed, or domain has no mail server.
Can it guarantee an inbox is valid?
No. It checks domain and SMTP-level deliverability, not whether a specific mailbox exists — some servers reject the probe by policy.
Is this safe to use on lists?
Yes — it does light SMTP probing only and is designed for deliverability checks. For large lists, use the API with batching and respect rate limits.
Powered by the DeFi Intel Agent Gateway (x402/MPP, USDC on Base). Free tier: 5 calls/day/IP. Prices from $0.001/call. For education — not financial advice.