Microsoft has announced a significant update regarding the deprecation of Basic Authentication (Basic Auth) for Exchange Online’s Client Submission (SMTP AUTH). Originally planned for permanent removal in September 2025, the timeline has now been extended to begin on March 1, 2026, with complete deactivation by April 30, 2026. This update provides organizations valuable additional time to transition to more secure authentication methods.
Why Basic Authentication Is Being Deprecated
Basic Authentication is a legacy protocol that transmits usernames and passwords in plain text, leaving them vulnerable to credential theft, brute-force attacks, and other security risks. To strengthen cloud security, Microsoft began phasing out Basic Auth across its services in 2019. Most Exchange Online protocols completed their transition to Modern Authentication (OAuth 2.0) by late 2022. However, SMTP AUTH, commonly used in applications, multifunction devices, and automated systems for sending emails, received an extended timeline due to its broad adoption.
Timeline for SMTP AUTH Basic Auth Deactivation
According to Microsoft’s latest communication:
- March 1, 2026: Microsoft will begin the phased deactivation of Basic Auth for SMTP AUTH.
- April 30, 2026: Full deactivation will be completed.
This transition will occur gradually, with Microsoft initially blocking a subset of Basic Auth attempts and then expanding the scope until all connections using Basic Auth are disabled.
Implications for Organizations
Organizations utilizing Basic Auth for SMTP AUTH must prepare for this change to avoid disruptions in email services. Microsoft recommends the following actions:
- Transition to OAuth: If your applications or devices support OAuth, configure them to use this more secure authentication method.
- Explore Alternative Solutions: For clients that do not support OAuth, consider the following alternatives:
- Microsoft 365 High Volume Email: Suitable for sending emails to recipients within your organization.
- Azure Communication Services Email: Designed for sending emails to both internal and external recipients.
- Exchange Server On-Premises: Organizations with a hybrid setup can configure their on-premises Exchange Server to allow anonymous relay or continue using Basic Auth within their on-premises environment.
Each organization should assess its current email infrastructure and update configurations before March 2026 to ensure uninterrupted communication.
How Fenestrae Can Help
Fenestrae’s Faxination platform is built to adapt seamlessly to evolving Microsoft standards and security protocols. As Basic Authentication sunsets, Faxination 2024 supports Modern Authentication (OAuth 2.0) for Microsoft 365 and Exchange Online, ensuring your fax and document workflows remain secure and uninterrupted.
Our team can help you:
- Transition your fax and email integrations to OAuth-based authentication
- Maintain compliance with Microsoft 365, Azure, and on-premises Exchange environments.
- Enhance your message security and streamline digital communication processes across your enterprise.
By partnering with Fenestrae, your organization can future-proof its communication infrastructure and stay ahead of Microsoft’s evolving security landscape.
Prepare Today for a Smooth Transition
Microsoft’s decision to extend the Basic Auth deprecation timeline underscores the importance of balancing stronger security standards with customer readiness. Organizations should use this extended window to modernize their authentication methods and strengthen their security posture. With Fenestrae Faxination 2024, businesses can make this transition smoothly, ensuring compliance, continuity, and secure communications well beyond 2026. Talk to our team today for assistance.
