Concerns: pushword/newsletter
Sites using occurrence sender contexts with a central base_live_url: set SendContext(systemLinkBaseUrl: 'https://your-public-host') when creating occurrences. Serve /newsletter/unsubscribe/* there, and /newsletter/c/* when click tracking is enabled. The explicit base controls unsubscribe headers, the HTML/text foot and click redirects; omitted values retain existing defaults. No schema update is needed. Existing enrollment snapshots retain their original/default base; new occurrences snapshot the explicit value. See sending context.