For security reasons, it is not possible to use the email address listed in the domain's WHOIS record for SSL certificate validation.

The approval email for SSL certificates can only be sent to one of the generic email addresses  listed below:

admin@yourdomain.tld
administrator@yourdomain.tld
hostmaster@yourdomain.tld
webmaster@yourdomain.tld
postmaster@yourdomain.tld

The approval email address is to be chosen during the activation of your certificate.