[fbdab103]

My point was that I think it is bad user experience if my email is "jane.doe@", but autocorrect has me input "Jane.doe@" (something I have experienced before). As a user, I "entered the same thing". On a technical level, they are different, but a decision must be made as to what is the true representation.

Amusingly, the context of this thread was in using case-insensitive search for email fields, but if emails are truly case sensitive, this is all moot, because you can only do direct comparisons.

[giantrobot]

In practical terms e-mail addresses are case insensitive. So if on account creation your normalize the address (lower case, trim white space) and send a verification e-mail and they successfully verify you can safely derive an ID from that normalized address. It won't matter later if autocorrect tries a mixed case address since you normalize and compare it on the back end.

If you run into a case where their e-mail server enforces case sensitivity they have bigger problems to deal with. E-mail has long been a system that requires loose adherence to the specs.