Add-on domains don't appear under email settings

[optize]

Example,

Main domain is domain1.com, we added domain2.com and domain3.com as add-on domains, and blah.domain1.com as subdomains.

Under 'Email Accounts' it gives me the ability to select domains, there is domain1.com and blah.domain1.com.

Why isn't my sub domains in that list? How else would I create email accounts for my sub domains?

[optize]

I found the problem, customer does't manage DNS with us, so we deleted his DNS zone, if you do that, you can't add email accounts for that domain.

Silly?