Skip to main content
POST
SMTP Verify

Overview

POST /api/smtp/verify runs a fast, real-time SMTP deliverability check on one email address. It answers a single question: can this mailbox receive mail. It does not run the full validity report (domain trust, person footprint, breach signals). Use it when you only need the mailbox verdict, for example inline on a signup form or during list cleaning. The check performs a live MX and SMTP probe and typically responds in under 200ms.

Authentication

Works with an API key or an in-app session. For API access, pass your key in the Authorization header.

Request

email
string
required
The email address to verify.

Example request

Response

email
string
The email address that was checked (normalized to lowercase).
status
string
The mailbox verdict: valid, invalid, catch_all, accept_all, temporary_failure, blocked, timeout, or unknown.
deliverable
boolean
true when mail can likely be delivered to this address.
mailbox_exists
boolean
true when the recipient mailbox was confirmed to exist.
catch_all
boolean
true when the domain accepts any recipient, so the specific mailbox cannot be proven over SMTP.
mx_host
string
The mail server (MX host) used for the probe.
disposable
boolean
true when the address uses a disposable or throwaway provider.
role
boolean
true when the local part is a role or shared mailbox (for example support@ or info@).
did_you_mean
string
A suggested correction when a likely typo is detected. Omitted when there is no suggestion.
checked_at
string
RFC 3339 timestamp of when the check ran.
credits
integer
Credits charged for this request (1, or 0 for a free repeat within the billing window).

Example response

Billing

This endpoint charges 1 credit per verification. Repeat checks of the same address are free for 6 months. That free window is shared with Email Validity, so a customer who has already verified an address on either endpoint is not charged twice.
For the full deliverability report (domain trust, person footprint, breach and disposable signals), use Email Validity instead. SMTP Verify returns only the mailbox verdict.