If you’ve already set up one domain in Office 365 operated by 21Vianet and you want to add a second domain, or other additional domains, follow the steps in this article. (To set up your first custom domain, on the Admin portal, on the Getting Started pane, click Email address.)
If you’ve already set up one domain in Office 365 operated by 21Vianet and want to add more domains, go to the Manage Domains page and choosing Add domain. The domains setup wizard will guide you step-by-step to add your domain.
