I am afraid you need to take this to the WordPress team because we just hook into their routines. but generally speaking, user ids and passwords are case sensitive

Hiya, just had another look at this, because another of my users got confused:

I think that the code involved might be sf-registration.php where it says:

 #  User not exists   
    if (!$user_email || $user_email != $_POST['email'])
        {
update_sfnotice('sfmessage', '1@'.__('This User Name does not exist!', “sforum”));
return false;
        }

I'm wondering if I change the != to something about case-sensitive, it might work? Of course, I'm a lot more likely to break it

My users do understand that their username and password need to be case-sensitive, but they get confused because the “reset password” function seems to need their email address to also be entered in the right case, and if not, it tells them that their username doesn't exist.

Cheers, I might try it.

For now, I've just changed the message to say that “Either that username does not exist, or the email address doesn't match it (NB. both are case sensitive).”