How do compromised ESP accounts cause widespread spam?

**ESP** accounts carry established reputation. Compromised accounts send spam through the legitimate sender's authentication and **IP reputation**, initially bypassing filters that would block unknown senders.

Scale amplification: ESPs enable high-volume sending. A single compromised account can send millions of spam messages before detection. The account owner's contacts and lists may also be targeted.

Collateral damage: spam from compromised accounts damages the legitimate sender's reputation, potentially affecting their deliverability permanently. **ESP** may suspend the account, disrupting legitimate business communications.