Verify-email.org offers verification tool for an email to check if the address is properly formatted and really exists.
This tool works as SMTP Server: MX-Records are extracted from a DNS Server. Then the tool connects to SMTP servers and simulates the sending of a message.
Verify-email.org offers API to be used for a website.
5. Do you provide API?
Yes. You can use the API to verify emails via our site if you are a registered user.
Read more: Verify-Email.org