The email verification service performs multiple checks on the email.
Hunter validates the format and make sure it isn’t a temporary address or a webmail. Then it contacts the mail server (without sending any emails) to make sure there is indeed an email inbox for the requested address.
Here's the list of checks that are performed on every email processed in the Email Verifier tool:
- Format: we verify the format of the email address is correct and looks something like "firstname.lastname@example.org". We also ensure the address doesn't look like a random email address. For example, email@example.com won't pass the test.
- Type: We check if the email address has a domain name used for temporary email addresses and we also verify if the email address uses a webmail like Gmail or Yahoo.
- Server Status: We check if there are MX records on the domain. If there aren't, the email address can't receive emails. We also perform a SMTP check to see if we are able to connect to the SMTP server (indicated in MX records).
- Email Status: We test the email address and see if it bounces or not and we check if the server has a catch-all policy which accepts all the email addresses.