1.0.0release11 Nov 2026
Initial verified release
The route is live and settlement-verified on Base mainnet. Health checks, public receipts and agent-readable records are available.
By APIStead Labs
VerificationVerifiedPreview
Email Verification API
Real-time email verification for AI agents, with a quality score.
APIStead LabsBase
About this API
Real-time email verification for AI agents. Before an agent sends a signup, invoice or outreach email, it should know whether the domain can receive mail. This API validates syntax, normalises the address, resolves MX records, detects null MX and implicit MX, flags disposable and role accounts, and suggests common domain typos.
The response includes a `verdict` (`deliverable`, `risky`, `undeliverable`, `unknown`), a `reason` code and a quality score from 0 to 100. It does not perform an SMTP handshake or prove that a mailbox exists, so it is safe to run at volume.
For AI agents
Check email syntax, domain and MX records before an agent sends a signup, invoice or outreach message.
Scope
Domain-level check only. Does not prove the mailbox exists, send a test message or perform SMTP probing. Disposable and role lists are curated samples, not a licensed feed.
Endpoints
| Method | Route | Price | Health | Description |
|---|---|---|---|---|
| POST | /email/verify | $0.001 | Verified · 3 ms | Verify email syntax, domain and MX records. |
Example request
request
POST https://apistead.qd.je/api/v1/email/verify
{"email":"hello@example.com"}Example response
200 application/json
{
"mx": [],
"note": "Domain-level check only. Mailbox existence is not confirmed and no message is sent.",
"email": "person@example.com",
"checks": [
{
"name": "syntax",
"detail": "Email syntax is valid.",
"status": "pass"
},
{
"name": "mx",
"detail": "No MX record was found.",
"status": "fail"
}
],
"domain": "example.com",
"reason": "no_mx",
"null_mx": false,
"preview": true,
"verdict": "undeliverable",
"checked_at": "2026-11-10T00:00:00Z",
"confidence": 0,
"disposable": false,
"suggestion": null,
"implicit_mx": false,
"accepts_mail": false,
"role_account": false,
"free_provider": false,
"mailbox_checked": false,
"normalized_email": "person@example.com"
}Verification
Verified1 of 1 routes verified
APIStead paid one named route from its own wallet, received real product back, and published the on-chain USDC receipt. The badge covers that route, not the whole listing.
- Last verified
- 13 Nov 2026
Use cases
- Clean a signup list before sending
- Block disposable addresses and role accounts in a workflow
- Catch common domain typos before they become bounces
- Reduce bounce rates for an agent-driven campaign
Agent intents
Phrases an agent can use to find this route.
validate an email addresscheck if an email domain can receive mailscreen an email before signupdetect a disposable email domain
Frequently asked questions
Does this API confirm that a mailbox exists?+
No. It verifies the domain and its mail route. It does not use SMTP, does not send a message, and returns mailbox_checked: false. A deliverable verdict means the domain can accept mail, not that the specific inbox exists.
What does the quality score mean?+
The quality score from 0 to 100 combines syntax, MX, implicit MX, disposable-domain, role-account and typo signals. It is a confidence indicator, not a guarantee of delivery.
Is this a real-time API?+
Yes. The API performs the domain and MX checks during the request and returns a structured result in one call. It does not run a slow SMTP mailbox probe.
Does it send email or use SMTP?+
No. The API uses DNS only. It does not connect to SMTP port 25, does not send mail and does not store the email address.
How much does a call cost and how do agents pay?+
A call costs $0.001 USDC on Base. The agent reads the x402 402 challenge, pays the provider wallet directly and retries. There is no API key or subscription.
What is a null MX record?+
A null MX record tells senders that the domain does not accept email. The API marks that domain as undeliverable instead of treating the missing mailbox as a temporary failure.