Email problem with subdomains

First issue that support have been unable to assist with :-( It seems you cannot configure email addresses on subdomains.

The error message is:

Subdomains such as uk.domain.com cannot be used in email addresses, so the accounts listed here belong to domain.com. 

So, if you have different offices around Europe, and use email addresses at uk.domain.com, de.domain.com, fr.domain.com, you cannot continue this on Cloud Sites :-(

Support were polite and friendly, but unable to offer a solution. I cannot see a technical reason why this isn't possible, and I guess I could setup a Cloud Server to work around this problem, though at additional cost.

I wonder if this is a problem for people that register domains like domain.uk.com or domian.gb.com through non accredited ICANN domain registries.