How do you tell if you have a domain-level or IP-level problem?

Distinguishing domain versus IP problems:

Gmail Postmaster Tools: Shows separate domain reputation and IP reputation scores.

Isolation testing:

Same domain, different IP: If problem persists, likely domain issue.

Different domain, same IP: If problem persists, likely IP issue.

Bounce message analysis:

IP-based blocks reference IP address or range.

Domain-based blocks reference domain name.

Blocklist checks: Some blocklists list IPs, some list domains. Check both.

SNDS: Microsoft's tool shows IP reputation specifically.

Domain reputation often harder to recover since it follows your brand. IP reputation can sometimes be escaped by changing IPs (but problems may follow).

Is the ship banned, or is the shipping company banned? Determining which drives the recovery approach.