In some edge cases, professional emails cannot be verified with the Email Verifier tool.

This could be caused by a blocked email domain or by an unresponsive email server.

In this scenario, you will see an unknown verification status, and the Email status for similar emails will be "Blocked".

This usually happens when the domain linked to the email is grey-listing or blocking our verification process, preventing Hunter from validating the email address.

In this case, it's best to attempt a new verification only after a few days to see if the block has been lifted.

In some occasional cases, Hunter can't verify an email address since the email server associated with it is unresponsive or due to another similar issue on the email server side.

As the verification cannot be performed at all, the following message will appear instead of the verification status: "We failed to verify the email address for reasons outside of our control. We advise you to retry later."

You can attempt a new verification after a few hours to check if the server can be accessed. Until we cannot verify the email, no verification credit will be used.