Basic Authentication has been part of email communication for decades. With SMTP AUTH, countless printers, scanners, applications, and websites were able to send emails automatically. But times have changed: Basic Authentication is no longer secure and Microsoft has officially announced that it will retire Basic Authentication for Client Submission (SMTP AUTH) in Exchange Online.
Even though SMTP Basic Auth is outdated, it’s still hiding in many environments today. Think of:
Printers and scanners that email scanned documents
Contact forms on websites
Internal or legacy applications that rely on simple mail submission
Often, these systems run in the background without anyone checking them. Until they suddenly stop working...
We’ve seen many clients unknowingly rely on devices or scripts that haven’t been touched in years. When changes like this hit, it’s often the silent dependencies (vendors, printers, monitoring tools) that catch people by surprise.
By being proactive, the disruption can be minimal. By waiting, the pain (downtime, costs, reputational risk) tends to multiply.
Ignoring this isn’t just “something to do later”: it could hit you hard, unexpectedly. Below are the potential impacts, drawn from real-world reports and vendor notices, to show what could break, and why it matters now:
| Wat kan brekenWhat could break | Real-world / vendor-reported examples | Why it’s serious |
|---|---|---|
| Devices stop sending emails | Once Basic Auth is retired, functions like scan to email, internet fax, automatic status/error notifications will fail on many of their devices. | These are often embedded in daily workflows; users might only discover the breakage when trying to scan or send a report. |
| Internal apps or scripts fail | Many legacy alerting tools, custom apps or scripts that use SMTP Basic Auth will no longer be able to send messages once Basic Auth is blocked. |
Could lead to lack of monitoring, missed alerts, or failure of automated business processes. |
| Operational downtime or disruptions | Organizations using Business Central noted email sending from within BC (notifications, document emailing) needs reconfiguration. | Business units may be unable to deliver invoices, reports, or customer-communications in time; this can hit customer satisfaction, compliance, and finance. |
| Security & compliance risks | Basic Auth doesn’t support MFA, conditional access. If credentials are stolen (via phishing, leaks, etc.), attackers can abuse them without additional checks. | Exposure to breach, data loss, reputational damage, regulatory fines depending on industry/region. |
| Surprise costs and firefighting | If devices or systems lack firmware or software updates to support OAuth, organizations may need hardware replacements + new integrations + unplanned support costs. | Budget hits, delays, more hours needed from IT staff; these surprises often happen under pressure, increasing risk of mistakes. |
📆 Microsoft will begin rejecting submissions using Basic Auth with SMTP AUTH gradually from March 1, 2026.
📆 Full enforcement (100% rejection) will be in place by April 30, 2026.
📆 Reports and tools (e.g. SMTP AUTH Clients Submission Report) are already or will be becoming available to show which sources are still using Basic Auth.
Check usage via logs (Azure AD Sign-in Logs: filter on SMTP & look for successes) to find where Basic Auth is still active.
Evaluate whether OAuth support exists — firmware updates, update code on apps, check vendors. If not possible, explore alternatives (relay services, updated tools, replacing hardware).
Prioritize high-risk & high business-impact systems — those that affect customers, revenue, compliance, or internal operations.
Plan for transition — set aside timeline, budget, test before change, communicate with users.
Microsoft’s retirement of SMTP AUTH is not a far-off change; it’s happening now. Taking action before it impacts your business is essential.
At Easi, we make sure our customers stay ahead of these changes. Here’s how we approach it:
Mailflow overview: We create a clear inventory of all possible SMTP Basic Auth sources in your environment.
Impact assessment: We identify which devices, forms, or applications will be affected.
Secure alternatives: We guide you toward modern, supported authentication methods that ensure your production keeps running smoothly.
ant to know if your company is still using SMTP Basic Auth? 👉 Contact us and we’ll help you make the transition without disruption.