How to diagnose multi-brand shared domain problems?

Identify contamination source:

• Which brand's sending correlates with issues?
• Review metrics per brand/stream
• Check complaint sources

Common problems:

• One brand's poor practices affecting all
• Combined volume exceeding safe levels
• Mixed reputation signals confusing providers

Solutions:

• Isolation: Move brands to separate subdomains
• Policies: Enforce strict standards for all brands
• Accountability: Track metrics per brand

Prevention:

• Separate domains/subdomains from start
• Shared domain policies enforced
• Regular auditing per brand
• Ships from same fleet share reputation. One problem vessel affects all.