Secure access to email and other business productivity tools continues to be a top priority for IT administrators. Microsoft services, such as Azure Active Directory and Office 365, use OpenID Connect for authentication and OAuth 2.0 for authorization. Here’s how that process works: When Outlook connects to Exchange Online, the API requests are authorized using OAuth 2.0 Access Tokens. They are valid for one hour. When the tokens expire, the Outlook client is redirected back to Azure AD to refresh them. This provides an opportunity to re-evaluate policies for user access. If a user has been disabled in the directory or because of a Conditional Access policy, the admin might choose not to refresh the token.
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