mainstream CPA networks do something similar

i signed up for one the other day and entered my domain but used @hotmail.com address

and they told me no can't do
email address must be from the domain from which you apply
also WHOIS data that doesn't match with email could be grounds to term

if it poses a threat, especially fraud joins, absolutely terminate them or alternatively give them a choice to submit an active url with content and @url.com email address to stay with your program