The reality is that the problem is fixable... by making sure to remove server errors onblur and we actually account for it in the code, but it is kind of overkill and not something you have to worry too much about since realistically it isn't going to happen very often if ever.
Curious...when you say "...by making sure to remove server errors onblur and we actually account for it in the code..." which lines of code in the original out-of-the-box contactus.php form are you referring to?