People might not arrive at your website outside of Office 365 operated by 21Vianet if they include "www" when they type the site address in a browser under certain setup conditions. This happens if you have a domain that you've added to Microsoft 365 and you've set up the domain so Microsoft 365 manages your domain's DNS. For example, if your domain is fourthcoffee.com , after you set up your domain and redirection to your website from Office 365 , people can get to your website by typing http://fourthcoffee.com in a browser. But they won't get to your website when they type http://www.fourthcoffee.com . You probably want both addresses to resolve to your website. You can make sure this works by adding "www" redirection . Do you manage your domain's DNS yourself outside of Microsoft 365 at your DNS host? In that case, you can set up redirection at your DNS hosting provider . Set ...