When you add an email address to your Outlook.com account, we send you an email asking you to verify the email address belongs to you.
To verify your backup email address, do the following:
If you're not already logged in to this account, log in using an email address that has already been verified.
Note: If you try to sign in using an email address that hasn't been verified, you'll be asked to verify it again.
Sign in to the email address you added and look for a verification email message in your inbox.
Open the verification email and click the link that says something like the following:
If you added this email address as an alias, use this link to verify: https://account.live.com/Aliases/Verify?aliasname=example
In Outlook.com, on the Manage your account aliases page, under Account aliases, you'll see the email address you added.