Microsoft 365 Migration Authentication: Methods, Permissions & Requirements

Microsoft has moved away from Basic Authentication and toward Modern Authentication based on OAuth. Microsoft Graph also supports two major access models: delegated permissions and application permissions. In this guide, we will explain the main authentication methods used with Microsoft 365 and how they relate to the SysInfo Office 365 Backup Tool.

Managing Authentication Methods in Microsoft 365

M365 authentication is the process used to verify a user’s identity before allowing access to Microsoft 365 services. For example, when the SysInfo Microsoft 365 Backup Tool connects to a mailbox, Microsoft needs to verify that the connection is authorized to access that mailbox.

Microsoft Graph authenticates the application through the Microsoft identity platform and controls its access to Microsoft 365 information. More information is available from Microsoft’s guide to Microsoft Graph authentication and authorization.

In simple terms:

• Authentication → verifies the identity
• Authorization → decides what can be accessed
• Access token → allows the authorized application to access the required Microsoft 365 data.

Why Is Authentication Important for Office 365 Backup?

• Connect the backup tool securely to Microsoft 365.
• To avoid sharing your primary account password with the application.
• Control which Microsoft 365 resources the application can access.
• Use administrator-approved permissions where required.
• Support modern security features such as OAuth-based authentication.

Microsoft 365 Migration Authentication Methods

1. Basic Authentication: An older authentication method in which an application uses a username and password to connect to a service. It was widely used by older email applications and scripts. However, Microsoft has discontinued Basic Authentication for many Exchange Online scenarios.

2. Modern Authentication: Preferred approach for many Microsoft 365 applications. It uses token-based authentication, commonly through OAuth 2.0 and Microsoft Entra ID. Instead of giving an application your Microsoft 365 password, the application can obtain an access token after the required authentication and permissions are completed. Benefits of Modern Authentication:

• Uses OAuth-based access tokens.
• Works with Microsoft Entra ID.
• Supports controlled permissions.
• Reduces the need to share passwords with applications.
• Fits modern Microsoft 365 security requirements.
• Can support application-based access for background operations.

3. Delegated Permissions: When there is an attempt by the application to access Microsoft 365 data through the account of a logged-on user. In such instances, the user logs on and authorizes the application to access particular data. This is done within the permissions that are available to both the user and the application.

4. Application Permissions: In application permissions, an application gains access to Microsoft Graph using its identity, and not via the identity of a signed-in user. This kind of permission is usually used in applications and services that do not require constant user interaction.

5. OAuth 2.0 Authentication: OAuth 2.0 is among the most important mechanisms in Modern Authentication. As opposed to using your Microsoft 365 password for the third-party application, OAuth enables the application to get an access token by going through the process of authentication and authorization. The Microsoft Graph needs an access token to allow API calls.

OAuth 2.0 vs Password Authentication

Authentication Methods for Microsoft 365 Using SysInfoTools

The SysInfo Microsoft 365 Backup Tool is designed to connect with Microsoft 365 and backup mailbox data to local formats. This tool offers OAuth and Azure App Authentication for Microsoft 365 connectivity. For a backup workflow, authentication is the first important step.

Microsoft 365 Migration Permission with SysInfoTools

1. Download the software. Select the available Microsoft 365 authentication method provided by the software.
2. For modern Microsoft 365 environments, use the supported Modern Authentication/OAuth-based option where available.
3. Choose “Primary Mailbox, Public Folder, Online Archive, or Shared Mailbox” to migrate. Click Next.
4. Select the saving format, apply features, and start the backup process.

Common Microsoft 365 Authentication Problems

• Incorrect Tenant or Application Details
• Admin Consent Is Missing
• Required API Permissions Are Missing
• Conditional Access Policies
• Expired Client Secret
• Incorrect Account Permissions

Microsoft 365 Authentication and EWS Retirement

There is another important change that Microsoft 365 administrators should keep in mind in 2026. Microsoft is retiring Exchange Web Services (EWS) in Exchange Online. Microsoft says EWS will begin being disabled globally in October 2026, with full retirement planned for April 2027. This matters because older backup and migration applications may still depend on Exchange APIs that are being phased out.

For this reason, businesses should check which APIs and authentication methods their backup software uses before starting a long-term Microsoft 365 backup project. Microsoft is moving applications toward Microsoft Graph to replace EWS dependencies.

Conclusion

There are several authentication methods for Microsoft 365. It regulates the process of identifying the backup application and which Microsoft 365 data can be accessed. As far as modern Microsoft 365 implementations are concerned, the major concepts to know are Modern Authentication, OAuth 2.0, Microsoft Entra ID, Delegated Permissions, and Application Permissions.

Frequently Asked Questions

About The Author:

Simran Bhatia

Simran Bhatia is a technical content writer engaged in writing clear, concise, and SEO-optimized content. With a background in computer science and a passion for writing, I thrive to deliver complex technical content in simple layman terms.