In theory emails are case sensitive. But using emails as system login I want them to be all lower case (i.e. [email protected] and [email protected] cannot be different users).
Can this be a problem for some users who use case sensitivity in their email address? Does somebody use it out there?
Edit: Because there are many "preserve case on save, ignore on login" answers: This system would break if I really had two different users john@smith and John@smith, wouldn't it?
Example: john@smith and John@smith have the password 123. How do I know which one just authenticated?
Some systems are case sensitive.
I'd suggest it be preserved but ignored a la windows filesystems.
i.e. remember john signed up with [email protected] but let him log in as [email protected], [email protected] or [email protected].
It's unlikely to cause conflicts and if anyone has a case-sensitive email I'm sure they'll be aware of it.