As of June 16, 2021, Sectigo no longer accepts WHOIS-based email addresses for Domain Control Validation (DCV) when the WHOIS requires a human lookup for domain information. Whois is a widely used Internet record listing that identifies who owns a domain and how to get in contact with them.

The change won’t affect emails that can be found on WHOIS via automated lookups. These emails will be presented to you during the certificate request process, or via the ‘GetDCVEmailAddressList’ API. The ‘constructed’ email addresses will still be available.

If the email address you need is not displayed or offered during the DCV process, you will need to use one of the alternative methods for the Domain Control Validation below:

Source: Sectigo’s Knowledge Base