Why doesn't Virgin Media Accept Correct Email Addresses?

Signed up for full fibre, and the whole experience as been let down because Virgin Media do not accept hyphens in domain names. A hyphen in a domain name is perfectly valid, and the email address that I have had for over 20 years has a hyphen in the domain name part.

I could not create an account until a dusted off an old gmail account. The web page just kept on telling me the email was invalid (in fact any email with a hyphen in was barred). Access top this forum also didn't work as it failed to send out the confirmation email until I had again used the old gmail account.

This is pretty basic stuff Virgin Media, you shouldn't get it wrong.