Hi Bruno,
I think that would defeat the purpose of the validation because we don't always get pre-verified email addresses and in some cases we get no email address at all and have to prompt the user for it.
In the case where we do know that the email provided by RPX is verified we do accept it without doing our own verification. There is an indicator in the data returned from RPX that tells us if the email is verified and we use this to decide whether to send our own verification email.
It varies from one account provider to another whether they provide a verified email address or not, but RPX does tell us if it is verified.
Best,
Joe