How to protect remaining healthy IPs or subdomains?

Strict traffic separation:

• Do not route problem segments through healthy IPs
• Do not mix affected domains with clean ones
• Keep transactional isolated from marketing

Monitor actively:

• Watch healthy assets for any reputation decline
• Check postmaster tools daily
• Alert on any metric changes

Preventive measures:

• Reduce volume even on healthy streams
• Focus on highest-quality segments
• Avoid any experimental sends

Contingency planning:

• Have backup sending ready
• Know how to reroute quickly if needed
• Healthy infrastructure is valuable. Protect it from contamination.
• Keep clean ships away from damaged ones. Prevent spreading the problem.