Ricoh scan-to-email fails with "535 5.7.139 Authentication unsuccessful, basic authentication is disabled"

Cause: Microsoft is disabling Basic authentication for SMTP AUTH in Exchange Online. Ricoh's own advisory confirms this breaks Scan to Email, Internet Fax, and automatic error/toner notifications — not just scan-to-email. See Ricoh's advisory and OAuth 2.0 setup guide.

Your options:

1. OAuth 2.0 if your Ricoh model/firmware supports it (the official fix) — see the Ricoh guide above.
2. A relay that still accepts a plain username/password, if OAuth isn't available on your model. ZeroSMTP is a free one built for exactly this case: change the SMTP server, port, and credentials in Web Image Monitor (Device Management → Configuration → Email), nothing else on the device changes. Mail sends from a shared @msgwing.com address, not your own domain, so it's a fit for internal notifications, not customer-facing mail.

Full guide (every option, per-brand printer settings, PowerShell audit for finding affected mailboxes): https://docs.msgwing.com/EXCHANGE-ONLINE-SMTP-AUTH.html and https://docs.msgwing.com/PRINTERS.html