How do ESPs communicate feedback to ISPs?

ESPs maintain multiple communication channels with ISPs:

Postmaster relationships where ESP deliverability teams have direct contacts at major providers for escalating issues and coordinating solutions.

Abuse desk communication for responding to ISP complaints about specific senders and demonstrating enforcement action.

Certification programs like Return Path Certification (now Validity) that establish ESP credibility through third-party verification.

Automated feedback through FBL enrollments, Postmaster Tools access, and SNDS monitoring that ESPs aggregate across customers.

Technical standards compliance demonstrating commitment to authentication, best practices, and industry guidelines.

ESP-ISP communication is like diplomatic channels between shipping companies and port authorities. Established relationships help resolve problems faster and maintain mutual trust.