"dash (-)" not allowed in (email)-domain

Hi,

i got the problem with one of my customers . When i try to add an email adress - which is in this case xx@xx-xx.com it tells me that it is invalid. I have to remove the dash in the domain name. But a dash is bind conform and should be recognized as valid.

Is there any workaround for this issue as the email adapter also uses this email adress. So the customer doesnt get email notification at all.

thanks for you help

andy