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Abigail Mundy, Product Marketing Specialist

Office 365 Is Retiring Basic SMTP—Here’s Your 3‑Step Plan Before March 2026

Last updated Feb 25, 2026

Step 1: Understand the Change

Remember when one key unlocked every door in the building? Handy—until someone made a copy.

That’s essentially how Basic SMTP Authentication works. Devices store a username and password and use it to send email through Microsoft 365. The problem? Basic authentication can’t enforce multi-factor authentication (MFA) and is vulnerable to password spray and brute-force attacks.

Microsoft is now phasing it out.

Updated Timeline (As of Microsoft’s Latest Guidance)

  • Now through December 2026: No change in behavior. SMTP AUTH Basic Authentication continues to work as it does today.
  • End of December 2026: Basic Authentication will be disabled by default for existing tenants. Admins can still re-enable it if necessary.
  • New tenants created after December 2026: Basic Authentication will be unavailable by default. OAuth will be the supported method.
  • Second half of 2027: Microsoft will announce the final removal date.

So while this is no longer an immediate hard stop, the direction is clear: Basic Authentication is going away.

Typical failure code: 550 5.7.30 Basic authentication is not supported for Client Submission

The goal is simple: move organizations away from password-based authentication and toward secure, token-based access.

Step 2: Meet OAuth 2.0 & Choose Your Path

Instead of storing passwords on devices, OAuth 2.0 uses short-lived, encrypted tokens.

Tokens:

  • Can be scoped to specific tasks (like “send mail only”)
  • Can require MFA
  • Can be revoked instantly
  • Don’t break when a user changes their password

Why tokens win:

  • No stored passwords → fewer credential‑theft risks.
  • MFA‑ready → aligns with modern security policies
  • Granular permissions → devices get only the access they need.

Your Three Paths Forward

Path 1: Implement OAuth Tokens (Recommended)

Best for: Modern devices that support OAuth (often via firmware update)

Implementation steps

  1. Verify the device’s firmware level.
  2. Register the device/application in Azure AD.
  3. Generate an OAuth token.
  4. Configure the device with the token and tenant details.

Many major manufacturers now support OAuth:
Ricoh
Canon
Kyocera
HP
Toshiba
Lexmark

If your fleet is relatively current, this is typically the most secure long-term solution.

Path 2: Stay Within Microsoft 365

Best for: Applications that can’t use OAuth but still need Microsoft-native routing.

Options include:

  • High Volume Email for Microsoft 365 (internal recipients only)
  • Azure Communication Services Email (internal & external recipients)
  • Exchange Hybrid Relay (on-prem receive connector + relay)

These solutions keep you inside the Microsoft ecosystem while reducing reliance on stored credentials.

Path 3: Use a third‑party SMTP relay

Best for: Legacy hardware with no firmware path forward.

Examples include:

These services may still allow username/password authentication but introduce additional cost, configuration complexity, and vendor management considerations.

Step 3: Execute & Verify

Don’t wait for 2026 to figure this out.

Start now:

  1. Audit every device and application using SMTP AUTH.
  2. Categorize each one as OAuth‑capable, Microsoft relay, or third‑party relay.
  3. Update firmware where possible.
  4. Plan hardware refreshes where needed.
  5. Document token creation and renewal procedures.
  6. Monitor for the 550 5.7.30 error.

Early planning prevents last-minute disruptions.

How Applied Innovation Can Help

  • Firmware upgrades: Customers with an active Maintenance Agreement can open a Service Call and we’ll update supported devices.
  • Token hand‑off: Once your IT team generates the OAuth credentials, our networking techs will populate them on your printers or copiers.
  • Strategic planning + support: Need a roadmap? We’ll help you weigh Microsoft relay vs. third‑party services and outline a phased rollout.

What we don’t do:
For security and compliance reasons, Applied Innovation does not:

  • Generate OAuth tokens on your behalf
  • Configure third-party SMTP relay services

We collaborate closely with your IT team to ensure a smooth transition.

Useful Resources

Bottom Line

Microsoft has extended the runway, but not the destination.

Basic Authentication isn’t disappearing tomorrow. But it is being phased out, and security expectations aren’t loosening.

Start auditing now. Choose your path. Modernize on your timeline, not during a service disruption.

Need a hand? Let’s talk.

Chat With An Expert

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