3eb3e94bce
Unset or malformed hostname makes the panel and Postfix diverge on SASL realm silently (auth breaks for every application) and breaks HELO/PTR matching (spam), so entrypoint.sh now exits before postfix-config.sh / supervisord with an explanatory error, plus a syntax check rejecting missing dots, schemes, ports, and whitespace. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>