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Werk #22004: Show sendmail output when mail delivery fails

Component Notifications
Title Show sendmail output when mail delivery fails
Date Jul 21, 2026
Level Trivial Change
Class Bug Fix
Compatibility Compatible - no manual interaction needed
Checkmk versions & editions
3.0.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Previously, when sending an email through the local sendmail command failed, Checkmk only reported the process exit code, for example:

sendmail returned with exit code: 1

That left you guessing about the actual cause of the failure.

Checkmk now captures the standard error and standard output of the sendmail command and appends them to the error message. The reason reported by sendmail itself is now part of the message, which makes diagnosing failed mail deliveries much easier.

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