How do ISPs, ESPs, and blocklists communicate?

Communication happens through multiple channels. Feedback loops let MBPs report spam complaints directly to ESPs. Blocklists publish real-time query interfaces (DNSBL) that receiving servers check during mail processing. Industry forums like **M3AAWG** enable direct relationships between players.

Postmaster teams at major MBPs maintain relationships with legitimate high-volume senders. ESPs cultivate these relationships to resolve delivery issues and stay informed about policy changes. Blocklist operators provide delisting processes and sometimes direct communication channels.

Much communication is automated: DNSBL queries happen programmatically, **feedback loop** reports arrive via standardized **ARF** format, and **DMARC** reports flow through email. Human communication focuses on escalations, policy discussions, and emerging threat coordination. Both layers are essential.