I have never aborted signing up because the form asked for the same information twice. Nor can I imagine doing so if it was obviously intended.

I could've done A/B testing and I could've done a full statistical analysis of the results. But I don't think splitting hairs like that is particularly useful. I simply had no reason to believe that it would affect our growth negatively, nor do I have such reason now. We are growing very, very fast.

But what I was really referring to was the customer service overhead. Almost every account that had a failed e-mail address would cause us some customer service. People creating another account which needed approval to prevent multiple accounts per user (which is cheating the game), or just asking questions. I cannot imagine people asking less questions if they paid for an account and can't access it.