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What is an Unknown email address?


These emails were unable to be validated due to various reasons such as mail server downtime or anti-spam systems blocking our verification attempts.

While we have great accuracy in identifying an email address as CLEAN or DIRTY, but there is always a chance when we are unable to do so. So, instead of blindly categorizing such email addresses as Clean or Dirty, we share transparency with you and categorize these addresses as UNKNOWN.

As, we are unable to positively categorize these addresses into any bucket, so now it’s up to you to decide whether you really want to reach out on such Unknown email addresses.


No Charges for Unknown Results: We understand the importance of accurate results, which is why we do not charge for unknown results. Any credits associated with these results will be promptly credited back to your account.

Safe for Sending: If you have a dedicated email server with your own IPs, unknown emails are typically considered safe for sending.

Not Safe for Sending: However, if you use a third-party email provider that enforces a bounce rate below 5%, these unknown emails should not be sent to maintain your deliverability standards.

NOTE: Many servers have a rate limit on SMTP verification. Due to this they don’t provide the information once the limit is reached for that particular hour. You can re-upload your UNKNOW file again after 1-2 hours and 1-2 days so that you will get more CLEAN and DIRTY from the UNKNOW. As we don’t charge for UNKNOW you can upload it again.

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