How do ESPs detect spoofed senders?

ESPs verify that senders control claimed domains through authentication setup requirements. Before allowing sending from your domain, ESPs require **DNS record** configuration proving domain ownership.

Ongoing verification includes: comparing sending patterns against expected behavior, monitoring for sudden changes suggesting compromise, and checking authentication consistency across messages.

Abuse detection systems flag suspicious activity: new accounts sending high volumes, content patterns matching known spam campaigns, and authentication configurations that appear designed to deceive. These systems protect **ESP** reputation by preventing abuse.