Once you've enabled 2 -step verification for your iCloud account, you have to generate an app-specific password to add your account to the Outlook app. Select Password and Security.

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.

When you send a digitally-signed macro or document, you also send your certificate and public key. Certificates are issued by a certification authority, and like a driver’s license, can be revoked.

Once you've downloaded the app from the Apple App Store, sign in with your work or school account to access content from your device. For help signing in see SharePoint app Sign In Help.

With two-step verification, you'll get a security code to your email, phone, or authenticator app every time you sign in on a device that isn't trusted. Need more help? If you have problems signing in with two-step verification, get more information at Having trouble with Two-factor Authentication.

Adding a Microsoft SharePoint account to the SharePoint app is easy when you've signed in to Microsoft 365 before. You'll follow the same steps in the app. If this is your first time signing in to Microsoft 365, you can read more in the topic, Where to sign in to Microsoft 365.

Open the app, go to the app's top-level menu, and then select Send feedback. After that, contact Support or go to the Microsoft Authenticator app forum and explain the problem you're seeing and the steps you tried.

If you try to sign in using a passkey and see the error message "We couldn't use your device to verify your identity," it means the passkey is no longer valid on that device.

We're sorry you're having trouble with your OneDrive for iOS mobile app. Let's get the issue sorted out as quickly as possible. Note: Some apps and features may only work with Wi-Fi, depending on your device settings, or your mobile data plan.

Outlook for iOS will detect a sync error and will ask you to enter your password again. If you are having difficulty getting Outlook for iOS to sync with your new password, delete your email account and then re-add it.