Microsoft SMTP Basic Authentication Retirement: The 2026 Guide for UK Businesses

Microsoft has officially confirmed the retirement of SMTP Basic Authentication for Exchange Online. While the transition began in 2025, the final deadline in 2026 marks a critical turning point for UK businesses.

To avoid the sudden failure of “Scan-to-Email” functions, automated invoices, and toner alerts, organisations must transition to Modern Authentication (OAuth 2.0). At Dragonfly Tech, we are helping our clients navigate this shift to ensure their print and IT infrastructure remains secure and operational.

What is Changing with Microsoft 365 SMTP in 2026?

For years, multi-function printers (MFPs) and legacy applications have used a simple username and password to send emails via Microsoft 365. This is known as Basic Authentication.

However, Basic Auth is a significant security vulnerability. It doesn’t support Multi-Factor Authentication (MFA) and is easily targeted by cyber-attacks. By retiring this legacy protocol, Microsoft is mandating a shift to Modern Auth (OAuth 2.0)—a token-based system that is significantly more secure and compliant with UK GDPR and Cyber Essentials standards.

How the SMTP Shutdown Affects Your Office Hardware

The most common point of failure for UK businesses will be their Scan-to-Email workflows. If your scanners or software systems rely on stored credentials, they will stop working as soon as Microsoft disables the protocol for your tenant.

Impact on MFPs

Many older Toshiba or Epson devices were built before OAuth 2.0 became the industry standard. If your hardware isn’t updated, you may experience:

• Failed Scan-to-Email Jobs: Critical documents won’t reach clients or internal folders.

• Broken Automated Notifications: Missed toner alerts and service requests.

• Workflow Bottlenecks: Manual workarounds will slow down your administrative teams.

5 Steps to Prepare Your Business for the 2026 Deadline

To ensure a seamless transition and zero downtime, the Dragonfly technical team recommends following this 5-step audit:

1. Audit Your Device Fleet: Identify every printer, scanner, and application currently using SMTP credentials.

2. Review M365 Usage Reports: Check your Azure AD (Entra ID) sign-in logs to see which devices are still using legacy “Basic Auth.”

3. Perform Firmware Updates: Most modern MFPs can support Modern Authentication through a firmware update.

4. Configure OAuth 2.0 or App Passwords: Switch your settings to use token-based authentication or a secure SMTP relay where hardware supports it.

5. Test Your Workflows Early: Don’t wait until the 2026 deadline. Run a “Modern Auth” test now to confirm your scanners are compliant.

Future-Proofing Your IT Security with Dragonfly Tech

Transitioning away from Basic Authentication isn’t just a technical requirement—it’s an opportunity to strengthen your business’s cyber defenses. Modernizing your print environment reduces the risk of credential theft and ensures your business remains at the forefront of digital security.

Is your hardware ready for the 2026 switch-off?

Contact Dragonfly Tech for a Security Audit and Firmware Check