How to test reputation independently by domain?

Testing domain reputation independently requires isolated measurement:

Inbox placement testing using seed list services that measure each domain's deliverability separately across major providers.

Postmaster Tools monitoring configured for each domain, tracking individual reputation scores and metrics.

Controlled test campaigns sending identical content from different domains to identical seed panels, revealing domain-specific treatment.

Authentication testing verifying that each domain passes SPF, DKIM, and DMARC independently without shared dependencies.

Blocklist checking querying each domain and its associated IPs separately against all major lists.

Independent testing is like inspecting each ship in your fleet separately. Overall fleet status matters less than understanding each vessel's individual seaworthiness.