AGPC Domain Check
Check a domain's SPF, DKIM, DMARC and MX with a graded shareable report

Email address validation.
mailboxlayer API is a free Email API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Enhance data quality with Mailboxlayer’s Email Validation API. Verify emails in real-time, reduce bounce rates, and prevent fake sign-ups for reliable communication..
Details from mailboxlayer.com.

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Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Check a domain's SPF, DKIM, DMARC and MX with a graded shareable report
The mailboxlayer API is provided by Mailboxlayer (mailboxlayer.com). Enhance data quality with Mailboxlayer’s Email Validation API. Verify emails in real-time, reduce bounce rates, and prevent fake sign-ups for reliable communication..
Yes. The mailboxlayer API is listed in the Email category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The mailboxlayer API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the mailboxlayer API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The mailboxlayer API is served over HTTPS, so it's safe to use in production.