Users remember their emails, they don't always remember their nicknames especially if they had to select an alternative nickname because the one they usually ch

Users remember their emails, they don't always remember their nicknames especially if they had to select an alternative nickname because the one they usually chose was already used... Honestly, it's ruthlessly pragmatic business reasons. Is it ideal? No but in the end, it's the most painless for most users... And, also most users on that particular site have little computer experience, so it does affect how they react and how we work. If it were something targeting the HN crowd, I'd probably have enforced email validation and would see a much lower drop in conversion due to it because people on HN are used to that and do not have a problem with it. So, validations and UI workflow have to be adapted to your audience and your business and that's the main point really. In this particular case, we did experiments with enforcing email validation for a subset of new signups or even allowing a small number of signups to signup with a username instead of an email. So we do have data... Most of the work I do for other customers doesn't touch those areas of their app, so I only have relevant on hand experience on that particular site but I think it's important to mitigate the recommendation of "Always validation emails" or "Always use regexp" and try to think of the best experience for the kind of users you're targeting. Sometimes in HN, people talk in absolutes when things are instead very context-dependent.