Modern Authentication is Microsoft’s OAuth 2.0‑based identity framework used across Microsoft 365 services, including Exchange Online, Outlook, and other Office applications.

Unlike Basic Authentication, which relies on transmitting username and password with every request, Modern Authentication uses secure token‑based access and advanced identity protections.

Modern Authentication provides a superior, secure, and future-ready authentication framework for Microsoft email services. It addresses the inherent vulnerabilities in Basic Authentication and introduces seamless integration with modern Microsoft 365 services.

Basic Authentication sends usernames and passwords with every request, creating multiple opportunities for attackers to intercept or steal credentials, especially in legacy or unencrypted scenarios.

Modern Authentication eliminates this by using OAuth access tokens that have limited lifetimes, are resource-specific, and cannot be reused across different endpoints.

Microsoft is removing Basic Authentication across Outlook.com, Exchange Online, EAS, POP, IMAP, and Remote PowerShell due to its security risks. Support for Basic Authentication is being phased out, making Modern Authentication the only viable method to remain compliant with Microsoft’s evolving security standards.

This means organisations that fail to adopt Modern Authentication will face:

As Microsoft retires Basic Authentication, any calendar integration relying on Basic Auth will eventually fail. Modern Authentication ensures continued functionality and uninterrupted access to calendar data.

If you'd like to know more about Modern Authentication or would like this implemented, this service is offered via our professional services team. Please reach out to your CSM or Support.