If it was “pulling teeth” just to get the ex’s email address and he’s never been involved with her schooling, then I’d wager that he’s lying about never have received the emails. I bet he never had any intention of filling out the form. The idea of tracing the emails, even if nyu agreed to do that, is really just silly. The emails were sent, he ignored them. Having nyu trace and say that the emails were truly sent to his email address gets you nothing. Heck, maybe he purposely gave you all an incorrect email address. Have your daughter send him an email, not related to this at all, and see if he responds.
This is all sad, yes, but with that average SAT for NYU, it is highly doubtful that your daughter would have rec’d much from them anyway. NYU’s need-based aid essentially has a merit component…meaning that even with need, the student needs high stats in order for nyu to open it’s pursestrings.
Try running nyu’s online net price calculator with just your financial info and copy/paste the results in your thread… if the results are inadequate with just your info, imagine how bad the results would be if your ex’s info had been included.