We know for certain that UA Failure occurs. Our testing shows that in the edge case of
unicode@idn.idn email addresses works less than 5% of the time. At the other end of the scale, an ascii@2nd.new4characterTLD works more than 90% of the time.
Toward addressing this issue, I would appreciate it if Registrars, ISPs & Hosting Providers - who are most likely to have direct engagement with registrants - could provide me - off list - some indication of their view of the scale of the problem based on evidence from your Help Desk system.
Thank you very much.
Don
Don Hollander
Universal Acceptance Steering Group
Skype: don_hollander