Stalwart 0.16.25 fixes DKIM key rotation failures

What changed

Stalwart released version 0.16.25 on 5 October 2026, fixing three DKIM key rotation problems. They affect operators using automatic DNS management or switching between automatic and manual management.

Previously, a rotation could retire the active key before its replacement reached DNS, leaving outgoing messages unsigned. A failed DNS write could also go unlogged while the task reported success.

Keys created under manual DNS management, or before DKIM records were published, could stop rotating after automatic management was enabled. Switching back to manual management could instead activate an unpublished key, causing signatures to fail verification and retirement of the old key to keep retrying.

What administrators should check

Review the release notes and upgrade instructions for your installed version. For domains already affected by stalled rotation after enabling automatic DNS management, the maintainers say rotation resumes once a DkimManagement task is created for the domain.

After upgrading, check rotation tasks and DNS publication, then inspect a delivered message from each affected domain for a valid DKIM signature. Review authentication reports for failures during the affected period. These are operational checks for Stalwart installations; the release introduces no general sender requirement.