Scope
Use timestamps, queue IDs, remote responses, source IP, VMTA, sender domain and message class to establish the failure boundary. Avoid reacting to one isolated delivery attempt.
Actions
- Reduce concurrency and injection for Yahoo routes
- Separate Yahoo/AOL metrics from global reporting
- Validate complaint feedback processing
- Review inactive and recycled-address exposure
Recovery
Restore volume in stages only after deferrals decline and accepted throughput is stable.
Operational rule: collect evidence before changing policy, make one controlled change, verify the result, and retain a rollback path.