Verification API

Stop bad emails at the front door

One GET request verifies any address in about a second — wire it into your signup form and fake, mistyped and disposable addresses never reach your database. REST, sane result codes, free tier.

Get your API keyView pricing
curl "https://api.mailtester.com/api/singlemail?secret=YOUR_API_KEY&[email protected]"

# Response
{
  "Result": "ok",
  "Reason": "accepted_email",
  "Role": false,
  "Free": false,
  "Disposable": false,
  "Spamtrap": false,
  "Did_you_mean": null,
  "User": "jane",
  "Domain": "acme.com",
  "Email": "[email protected]"
}
What you get

Production-grade from the first call

API features and limits
Single verification endpointGET /api/singlemail — full verdict with reason in ~1s median
Bulk verificationFile upload API for whole lists, with progress and result download
AuthenticationAPI key via the secret parameter — separate keys per project, rotate anytime
Rich result payloadRole, free-provider, disposable and spam-trap flags plus did-you-mean on every check
Typo correctionDid_you_mean catches fat-fingered domains before they enter your database
Official librariesPHP, Python, Ruby and C# — open source at github.com/mailtester-com, or call the REST endpoint from anything
Plan-based rate limitsScales with your subscription; custom limits on Business
Free tier100 credits on every new account, no card required
Result codes

Three verdicts. One reason code.

Every response maps to one clear action — ok, fail, or risky — with a machine-readable reason explaining exactly why.

  • ok

    Mailbox exists and accepts mail. Safe to send.

  • fail

    Mailbox or domain does not accept mail. Remove it.

  • risky

    Deliverability uncertain — catch-all, disposable, spam trap or disabled mailbox. Check the Reason field and segment.

  • Reason

    Every verdict carries a machine-readable reason (accepted_email, email_disabled, …) so your code can branch precisely.

Use cases

Where teams put the API to work

  • Signup form validation

    Check the address while the user is still on the form. Block disposables, catch typos with did-you-mean, and keep fakes out of your database entirely.

  • CRM hygiene automation

    Verify contacts as they enter your pipeline and re-verify on a schedule, so sales never wastes a sequence on a dead mailbox.

  • Lead enrichment pipelines

    Score purchased or imported leads before anyone mails them — the Reason field tells your pipeline exactly why an address failed.

  • Batch jobs at scale

    Verify whole tables via the bulk file API and pull segmented results back into your warehouse when the job completes.

Validating one address at a time in a UI instead? See single email verification, or bulk list cleaning for whole files.

API calls use the same credits as everything else

No separate API pricing, no monthly minimum. Credits from $19, down to $0.0003 per verification at volume — and they never expire.

See full pricing

How many emails do you need to verify?

50,000credits

$79

$0.0016 per email

FAQ

Developer questions

First 100 API calls are on us.

Create an account, grab your key, and your signup form is protected before lunch.

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