Failure mode: discovery-time status equals send-time status

Failure mode: discovery-time status equals send-time status
Mistake: you verified the 404 three weeks ago. By send day, the owner fixed it. Your pitch points at a now-live page. Credibility gone.
Fix verification gate:
— 1. Treat status as perishable — valid for 72 hours max.
— 2. Run an automated re-check on the entire batch the morning of send.
— 3. Any URL that resolved to 2xx/3xx → pull from batch immediately.
— 4. Log the re-check timestamp beside each send.
— 5. QA gate: send blocked if last status-check is older than 72h.
Automation: pre-send batch HEAD request as a hard pipeline step.
Definition of done: no email ships referencing a URL not re-confirmed dead within 72 hours.