When adding domains to Office 365 management, you may receive an error:

 

"You've typed a domain name that includes an extension that is not valid. Type a domain name that includes .com or another valid extension."

 

Try the following:

 

1. Check the list of countries that Office 365 is available in to see if your domain may be supported. Check the list of countries' restrictions here: About license restrictions for Office 365.

 

2. Try adding the domain to your Office 365 account by using the "New-MsolDomain" cmdlet for Windows Powershell.

To try adding a domain using PowerShell, follow these instructions. In these instructions, the domain EXAMPLE.SO is going to be added. In this example, .SO is the third level domain (TLD) for Somalia and therefore can't be added through the Add a domain wizard at the Office 365 portal.

  1. Make sure you have installed the necessary additions for Windows Powershell to manage Office 365, including Microsoft Online Services Module for Windows PowerShell. See this article for more information:  Use Windows Powershell to manage Office 365 .
  2. Open Windows Powershell by opening the link on your desktop: "Microsoft Online Services Module for Windows Powershell". If this link doesn't appear, search for "Windows Powershell" in Start.

  3. Load the module for Microsoft Online Services into Powershell by typing "import-module MSOnline" (without quotation marks) and press [Enter]. You can skip this step if you opened the "Microsoft Online Services Module for Windows Powershell" link on your desktop.

  4. Connect to your Office 365 account by typing "connect-msolservice" (without quotation marks) in the command module and pressing [Enter].

  5. Login with the administrator login details for your Office 365 account in the dialog box that appears. These are the same credentials you use to login as an administrator on the Office 365 portal in your browser. You're now connected to your Office 365 account in Windows Powershell.

  6. Add a domain to your account by using the "New-MsolDomain" cmdlet with the "name" switch to specify the domain you wish to add. e.g. to add EXAMPLE.SO as a domain, type "new-msoldomain -name example.so"  (without quotation marks) and press [Enter].

  7. A summary of the domains you have added will appear in a table with headings Name, Status and Authentication. Your domain will have a status of "Unverified" for the moment.

  8. Close Windows Powershell.

  9. You can now return to the the Office 365 portal in your browser and go through the verification process for your newly added domain. Login into Office 365 as an administrator and select Domains under the Management header in the left menu. Follow the verify link for your newly-added domain to complete the Add a domain wizard as normal. 

If you want to add subdomains for the domain you've just added, just follow the steps again. e.g. to add the subdomain LABEL.EXAMPLE.SO, login to Microsoft Online Services through Windows Powershell using the steps above and type "new-msoldomain -name label.example.so" (without quotation marks) and press [Enter].