Scan to email after Microsoft 365 turns off SMTP AUTH
Copiers that scan to email through smtp.office365.com with a password stop working when Microsoft 365 turns off basic authentication. These pages explain the errors and every way to keep scans arriving, including the free ones.
Start with your symptom
- The log says 5.7.139 basic authentication is disabled.
- The log says 5.7.57 Client not authenticated to send mail.
- Scans just stopped arriving.
- Nothing's broken yet and you want to get ahead of December 2026.
Where Scan Relay fits
Scan Relay is a small Windows program I make for the copiers the free options don't suit: no OAuth firmware, no static IP, scans that go to outside addresses, or nobody available to own a connector and SPF. It runs as a service on an always-on office PC. The copier sends to that PC on the local network (port 25, any username and password), and Scan Relay sends each scan on to Microsoft 365 through Microsoft Graph with OAuth, as the mailbox you signed in with.
- Works with any copier or scanner that can scan to email over SMTP, without a firmware update, static IP, connector or DNS change.
- Delivers to outside addresses as well as your own staff.
- Saves each scan on the PC first and retries if the internet drops.
- Limits, so you can decide: it needs a Windows PC that stays on; it sends up to about 3 MB per email (set the copier to split scans at 3 MB); a Microsoft 365 admin approves it once per organization; and the program isn't code-signed yet, so Windows SmartScreen shows a warning the first time. How it handles your mail.
Free for 14 days, then $99 once per office (one PC, any number of copiers). Full refund within 30 days if it doesn't work with your copier.
Scan Relay: free 14-day trialCheck if your copier is affected
Questions
Microsoft's January 27, 2026 timeline says it is disabled by default for existing Microsoft 365 organizations at the end of December 2026. Admins can still turn it back on, and Microsoft says it will announce the final removal date in the second half of 2027.
It's free, but it only delivers to mailboxes in your own Microsoft 365 organization, needs outbound port 25, and Microsoft recommends a static IP for SPF. Scans to outside addresses are rejected.
Yes, Microsoft lists printers and scanners as an HVE use case. It sends to internal recipients only, up to 10 MB per message, and is billed pay as you go through an Azure subscription.
$99 once per office after a free 14-day trial, covering one PC and any number of copiers. Full refund within 30 days if it does not work with your copier.
Related
- 550 5.7.139: basic authentication is disabled
- 535 5.7.139 and 5.7.57 Client not authenticated
- Scan to email stopped working with Office 365
- SMTP AUTH deprecation in December 2026 for copiers and MFPs
- Brands: Ricoh, Canon, Xerox, Konica Minolta, Sharp, Kyocera
- For IT providers managing many offices
- All the options compared · Will my copier break? (free check)