I haven't used that appliance but it certainly seems very strange. I'm assuming that the error relates specifically to the email field (as you say it does and the screenshot suggests that it does also). I'm also assuming that there are no space before or after the email.

Obviously that email address should be accepted going by convention. But have you tried any other combinations to see which character it's complaining about (even if it shouldn't). eg try an email without the "." it may also be worth trying a name without the @whatever.com. I have seen some odd systems that don't like the "@" symbol and require you to use a "+" instead, perhaps that is also worth a try?