I have a funny feeling you do not charge money for stuff. When regina123@aoll.com can't log in after paying $30 for the privilege to do so, it is my problem.

This was a problem I ran into. Originally my application did not require an email, but I ran into so many forgotten password cases that I eventually had to add one. And I felt it was my responsibility to help those users as most apps have that feature and usernames can be easy to forget.