DSM says Test mail failed to send. How do I restore email notifications?

Applies to: DSM system email notifications; individual packages may have separate notification settings.

Work through these checks

1. Open Control Panel > Notification and record the full test error, selected provider and sender method. Note whether every test fails or failures are intermittent. Never include passwords or authorisation tokens in a screenshot.
2. For a built-in provider, use its supported sign-in or reauthorisation flow. For custom SMTP, confirm the server, port, TLS mode, permitted sender and current authentication requirements with the mail administrator.
3. Check NAS time, DNS and the outbound path to that exact mail service. Ask the administrator to review rejected sign-ins or SMTP responses. Do not enable obsolete authentication tenant-wide or disable account protection as a workaround.
4. Send one test to the intended recipient and check spam, quarantine and delivery logs. Then review the notification rules for the required events; a successful test alone does not enable every event category.

Confirm the result

Confirm a test arrives with the expected sender and time, then verify the next genuine scheduled event produces its intended alert.

If you need help

Include these details in your ticket: DSM version, provider/method, complete redacted error, failure time and whether the message reached quarantine.

Updated 261107