Only difficulty I see here is that communication might have already been sent to the user about registration (welcome email). So user would be confused if registration succeeded why he is not able to login. Very bad user experience.
Also, it would be unwise to stop or delete queued email. You might not be sure if email was already sent. Or you need to send user a subsequent email about your registration has been revoked.
I would suggest to write a ActionFilter and do the post to API at that while action being performed. If it hits any obstacle, simply send to registration failure page. This would prevent the registration.
Thanks! i was thiking about ActionFilter too, can u sugest some implementation , or where to look !
Something like this https://www.pronopcommerce.com/overriding-intercepting-nopcommerce-controllers-and-actions i guess ?
Yes. That's the one. You should be good.