Postfix Engineering Center · Version 3.9

OpenDKIM Integration

Connect Postfix to OpenDKIM, define signing scope and verify results.

Engineering objective

This guide treats the setting as part of a complete mail flow rather than an isolated directive. Confirm the listener, trust boundary, queue behavior, DNS dependencies, authentication path and downstream transport before deployment.

Implementation workflow

1. Record the current effective configuration with postconf -n and relevant postconf -M output.
2. Define exactly which clients, senders, recipients or destinations the change should affect.
3. Apply the smallest explicit configuration change and rebuild any map with postmap.
4. Validate syntax using postfix check, then reload rather than restart when possible.
5. Run a controlled SMTP test and follow its queue ID through the logs.

Example pattern

# Document intent beside every non-default setting
# Verify effective values with: postconf parameter_name
# Validate configuration with: postfix check
# Apply safely with: postfix reload

Verification

• Confirm the effective parameter value, not only the text written in main.cf.
• Check that the expected master service and transport are active.
• Verify successful delivery and the intended failure behavior.
• Watch deferred queue age, reject rates and authentication failures after deployment.

Common failure modes

• A permissive restriction appears before the required reject decision.
• A map was edited but not rebuilt or the wrong map type was configured.
• A chrooted service cannot access a socket, certificate or resolver file.
• The test uses a trusted local client and does not exercise the public path.

Back to Postfix Engineering Center