This is a custom code modification. 

You need to add new regular expressions for these letters to the e-mail pattern :

const EMAIL_PATTERN = '/^([\w\-\.\+\%]*[\w])@((?:[A-Za-z0-9\-]+\.)+[A-Za-z]{2,})$/';

in the ow_utilities/validator.php file. 

Thanks Ross

No problem

Christer, I would not recommend you to add Scandinavian letters to the regexp, as this can affect your mass mailing as the phpmailer function wouldn't be able to parse it correctly. It is a common practice over the internet to use only latin alphabet, both in username, e-mail and other info, as this info is used all over the software, such as in url etc. 

Hi Ross
yes I looked around and it is what all using so nothing I want to start mess with. Thanks Ross