Go to Domain Rules under Account Settings of your web vault. You will see that by default, the list of Global Equivalent Domains defines the following domains as equivalent:
bing.com, hotmail.com, live.com, microsoft.com, msn.com, passport.net, windows.com, microsoftonline.com, office.com, office365.com, microsoftstore.com, xbox.com, azure.com, windowsazure.com
You can click on the gear icon (Options) for that global equivalence entry to delete it or customize it (the gear becomes visible on the right side when you hover you mouse over the entry).