Does this validator send an email or contact the mailbox?
No. It performs no SMTP probe and sends no message. It checks syntax, mail-routing DNS, and heuristic risk signals.
Free tool · no signup · no SMTP probing
Check an address before you send to it: syntax, real MX records, disposable and role accounts, and the typo you probably meant. No mail is ever sent, and nothing you type is stored.
API live at email.lifestep.ioNo. It performs no SMTP probe and sends no message. It checks syntax, mail-routing DNS, and heuristic risk signals.
No. Syntax and DNS cannot prove that a mailbox exists, is monitored, or will accept a future message.
True means usable mail-routing DNS was found through MX or the RFC 5321 address-record fallback. Null means the DNS result is unknown, not that the address is invalid.
Yes. It checks bundled domain and local-part lists and returns separate boolean fields, but those classifications are heuristics that can change over time.
The API can return a suggested corrected address for a nearby common provider domain. It does not automatically replace the submitted address.
curl -sS "https://email.lifestep.io/validate?email=test%40gmail.com" \
| jq '{normalized,syntax_valid,has_mx,is_disposable,is_role_account,is_free_provider,suggestion,score,verdict}'
Response sample for test@gmail.com using the stable validation fields:
{
"normalized": "test@gmail.com",
"syntax_valid": true,
"has_mx": true,
"is_disposable": false,
"is_role_account": false,
"is_free_provider": true,
"suggestion": null,
"score": 90,
"verdict": "deliverable_likely"
}
The validator code does not persist submitted email addresses. It caches only domain-level DNS results in process for up to 600 seconds; that cache is not shared or persistent.
Use the agent verification guide to separate hard syntax failures from reviewable DNS and risk signals, with explicit acceptance rules before any send or import step.