An SMTP server is responsible for sending emails. A "cracked" list contains login details—usually a —that have been stolen through:

: Using automated software to guess common passwords.

: Sending massive volumes of unsolicited emails.

: Reusing passwords leaked from other data breaches.

: Unauthorized access to your email infrastructure often indicates broader vulnerabilities in your network.

: Your legitimate business emails may be blocked by major providers (like Gmail or Outlook) because your server's reputation is ruined.

: Organizations may be held responsible for the malicious traffic originating from their infrastructure. How to Protect Your SMTP Server

Threat actors use these lists to bypass standard email security measures by leveraging the reputation of legitimate servers. Common uses include: