Inspect OpenSMTPD queue envelopes and delivery failures

OpenSMTPD queues a message and associated delivery envelopes. One message can have multiple recipient outcomes, so “the message was accepted” is not a complete delivery report.

Inspect before modifying

Use the installed smtpctl manual and the project’s documentation. A read-only starting point is:

smtpctl show queue

The command may require local administrative permissions. Inspect only the relevant instance and avoid copying recipient/message content into public diagnostics.

1. Identify queued envelopes and the affected recipients, not just an overall count.
2. Correlate logs with DNS/connectivity, temporary destination rejections, local MDA/LMTP failure, and authentication/TLS errors.
3. Check storage health and the service’s effective configuration.
4. Review the configured action: the configuration manual notes that action changes can affect subsequent attempts for already queued work.

Recover with an explicit decision

Fix the transport or destination problem before scheduling another delivery. Removal and forced retry are mutations that can lose or send real mail; do not use a blanket queue purge as troubleshooting.

After recovery, follow a controlled envelope to its final delivery/bounce outcome and check that a queued copy has not also been recreated by application retries. Preserve a consistent spool/configuration backup and test restoration on an isolated host before a production migration.