How can you identify complaint patterns by ISP?

Identifying complaint patterns by ISP helps diagnose provider specific issues. If complaint rates are elevated at one provider but acceptable elsewhere, something about your mail to that audience is problematic.

Monitor complaint rates per provider through FBL data and postmaster tools. Segment analysis may reveal that certain content, timing, or acquisition sources drive complaints at specific providers.

Provider specific patterns might reflect audience differences, delivery timing variations, or inbox placement affecting visibility. If complaints spike at one provider, investigate what differs about those recipients or how your mail appears at that provider.