Source policy

source

Operational reference for the PowerMTA source directive or configuration concept.

Purpose

source participates in source policy. Use it only after identifying the configuration scope, the message population affected, and the evidence that will confirm the change worked.

Syntax pattern

<source NAME-OR-SCOPE>
    # scoped directives
</source>

Scope and precedence

Confirm whether the setting is global, source-scoped, VirtualMTA-scoped, domain-scoped or pattern-selected. More specific policy can override a broad default, and overlapping matches can make the effective result different from the line being inspected.

Operational example

# Documentation example
# Replace placeholders and validate locally
source EXAMPLE_VALUE

Production guidance

• Record why this setting exists and which traffic it controls.
• Avoid copying values from unrelated infrastructures.
• Validate configuration syntax before reload.
• Review queue growth and remote SMTP responses after deployment.
• Keep a rollback copy of the last validated configuration.

Common mistakes

• Using the directive in the wrong scope.
• Assuming an example value is a universal recommendation.
• Creating overlapping rules whose precedence is unclear.
• Changing delivery policy without monitoring provider responses.

Validation

Confirm the effective routing or delivery result using a controlled test, configured logs, accounting output and the final received headers. Syntax acceptance alone does not prove the intended policy was selected.

Related