Should I capture email addresses in lowercase in an uppercase system?

Your opinions please.

In our system the decision was made that all fields (except not开发者_开发技巧es) will be forced into uppercase. I don't like it, but the system's intended users aren't very computer literate, so for line-of-business use I suppose it is acceptable.

When it comes to email addresses however, would you also force them into uppercase, against the lowercase convention?

The part before @ "Local Part" is "locally interpreted" (see RFC 2822 §3.4.1).

This could include being case-sensitive. Whether any email processing agents support case sensitivity is another question.

Email addresses are case-insensitive, so it doesn't matter. Upper case would be fine.