> Think of the average user. Sometimes they're going to capitalize the first letter when putting in their email, and sometimes they aren't. You don't want to make it unusually difficult for them to log in.
With smartphone keyboards and the capitalization of the first letter of the first word in form input fields by default, this is a very common occurrence. If case was considered for uniqueness of email addresses, at best, people would be extremely annoyed. At worst, there would be a tremendous amount of leakage of sensitive information to random people (due to human errors in entering case sensitive addresses), chaos due to incorrectly delivered emails and fatigue in receiving mails intended for thousands of other people. In an alternate universe where this is true, email would never have been a killer application, only a quickly killed and abandoned one. :)
With smartphone keyboards and the capitalization of the first letter of the first word in form input fields by default, this is a very common occurrence. If case was considered for uniqueness of email addresses, at best, people would be extremely annoyed. At worst, there would be a tremendous amount of leakage of sensitive information to random people (due to human errors in entering case sensitive addresses), chaos due to incorrectly delivered emails and fatigue in receiving mails intended for thousands of other people. In an alternate universe where this is true, email would never have been a killer application, only a quickly killed and abandoned one. :)