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Microsoft Is Pulling the Plug on SMTP AUTH in Exchange — December 2026 

Back in August, we wrote a blog post about Microsoft’s plan to disable SMTP AUTH. Now the deadline is rapidly approaching. 

How to Keep Your Printers, Scanners, and Apps Connected 

Microsoft is officially phasing out Basic Authentication for SMTP in December 2026. 

Microsoft Is Changing How Email Works — Here’s the Simple Way to Keep Your Devices Connected 

The 2026 SMTP update is coming, but keeping your printers and applications running is easier than you think with mySMTP. 

If your business relies on Microsoft Exchange Online to send emails from multifunction printers, scanners, IoT devices, or legacy applications, you are likely already aware of the ticking clock. Microsoft has announced the phase-out of SMTP AUTH (Client Submission), with a final sunset date scheduled for December 2026. 

While this move is a major step forward for global cybersecurity—forcing a shift toward modern authentication standards like OAuth 2.0—it places many IT administrators in a difficult position. 

Why? 

Because millions of devices and applications in offices worldwide simply do not support OAuth 2.0. They were designed to authenticate using a simple username and password. Once Microsoft disables this capability, those devices will no longer be able to send email. 

Below, we explain how the landscape is changing—and how mySMTP provides the bridge you need to keep your infrastructure running without replacing hardware. 

The Challenge: “Modern Authentication” vs. Legacy Reality 

Microsoft’s push for Modern Authentication is intended to protect user accounts from brute-force and credential-based attacks. However, in practice, upgrading an entire fleet of physical devices or rewriting legacy application code is often cost-prohibitive—or technically impossible. 

You may be dealing with: 

• ERP or accounting systems hard-coded to send invoices via port 587 

• Printers and scanners that only support “SMTP Server,” “Username,” and “Password” 

• IoT devices or alerting systems that cannot handle token-based authentication flows 

When April 2026 arrives, any system still pointing to smtp.office365.com using Basic Auth will stop working. 

The Solution: mySMTP as Your Compatibility Layer 

At mySMTP, we specialize in being the reliable email delivery engine for exactly these scenarios. We understand that while security is critical, operational continuity is non-negotiable. 

Here’s how mySMTP supports customers migrating away from Microsoft’s legacy SMTP service: 

1. Plug-and-Play Compatibility 

In most cases, migrating to mySMTP is as simple as changing three fields in your device or application settings. Because we support standard SMTP authentication over secure TLS connections, there’s no need to update or replace your hardware. 

• Old setting: smtp.office365.com 

• New setting: (your mySMTP email eg: ”relay1.mysmtp.com”  

2. Dedicated IPs for Superior Deliverability 

With large shared services like Office 365, your transactional emails share sending reputation with millions of other users. mySMTP offers Dedicated IP plans, ensuring your automated emails are sent from an IP address used only by your organization. 

Your reputation is yours alone—so critical emails like invoices, alerts, and reports aren’t blocked due to someone else’s spam. 

3. Cloud-Based and GDPR-Compliant 

For European customers—and anyone concerned with data privacy—moving away from a US-centric provider can actually improve compliance. 

mySMTP is fully hosted within the EU, offering a secure, resilient infrastructure that respects data sovereignty while delivering enterprise-grade uptime. 

4. Built for “Non-Human” Email 

Microsoft Exchange is optimized for human-to-human communication. mySMTP is designed for machine-to-human messaging. 

We don’t throttle your scanner because it sent “too many” PDFs in an hour. Our platform is optimized for high-volume, transactional email—so your automated workflows won’t hit unexpected sending limits. 

How to Migrate in 3 Simple Steps 

Don’t wait until December 2026 to scramble for a solution. You can migrate your devices today—in just minutes: 

1. Create an account 
   Sign up at mysmtp.com and choose a plan that fits your email volume. 
2. Update your device or application 
   Log in to your printer, scanner, or app configuration and replace the Microsoft SMTP details with your mySMTP credentials. 
3. Optional: IP Whitelisting 
   You can also whitelist your sending device’s IP address, eliminating the need for SMTP AUTH altogether. 

That’s it. You’re now insulated from Microsoft’s deprecation timeline. 

Ready to test the migration? 
Start a free trial with mySMTP today and see how easy it is to switch.