Why are some of my domains not eligible?
When setting up your Office 365 or Business Email email accounts, you may see some domains listed as not eligible, or greyed out in the list. This is because you can only have a single email type for each domain.
If you've already set up Office 365 or Workspace email using a certain domain, you can't use that domain for a Business Email account. Or vice versa -- if you've set up a Business Email account on one of your domains, you can't use that same domain for Office 365 or Workspace email. However, if you've set up a Workspace email address on a domain, while you can't use that domain for a Business Email account, you can use it for Office 365.