You'll know that you're signed in with your Microsoft account by looking for the Sign in button on the Home tab in Windows Live Mail. When you're signed in, your display picture and display name will appear on the Sign in button.
You can sign in with your Microsoft account to use Mail with other Microsoft services. For more information about why you should sign in, see
Do I need to sign in with a Microsoft account to use Windows Live Mail?
On the Home tab, click Sign in.
Type your Microsoft account user name and password, select the check box if you want to always sign in with this account, and then click OK.
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