Users typically sign in by using their user principal name (UPN). We are working on an update to the Mac and iOS applications to support signing in by using an alternative user identifier. To resolve this issue, update to the latest version of Mac and iOS apps.

To fix the issue: Set up a new passkey. Check the authenticator app on your mobile device for any passkeys that no longer apply and delete them. "Sign in another way. We couldn't use your device to verify your identity" message.

Add your Outlook.com, Microsoft 365, or Exchange-based email account to your iPhone, iPad, or iPod Touch using the iOS Mail app.

You can add links and images to your email signature, change fonts and colors, and justify the text using the mini formatting bar under Edit signature. You can also add social media icons and links in your signature or customize one of our pre-designed templates.

Microsoft Authenticator is a mobile app that helps you sign in to all your accounts without using a password.

The tool will ask you to enter the email address or mobile phone number you're trying to sign in with and check the details you provide. If we detect a problem with your account, we'll tell you what you need to do to solve the problem.

Open the Outlook for iOS app on your iOS device. Select Add Account to add one of your existing email accounts, or Create New Account if you want to create a new Microsoft account.

To add an additional email account, tap your account menu in the top left corner in your Outlook app. Select the blue plus sign to add another account. Once you have multiple accounts added, you can easily switch between them.

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Once you confirm that you’re an administrator and using your Microsoft account, go back to the Activation page, select Add an account, enter your Microsoft account and password, and then select Sign in.