: Using multiple compromised servers to avoid being flagged by spam filters that limit the number of emails sent from a single IP. Security Implications

To help you further, are you looking to , or are you investigating a potential breach ?

: Using automated software to guess common passwords.

If you believe your server has been compromised, you should , review your server logs for unauthorized access, and check if your IP address has been added to any global RBLs (Real-time Blackhole Lists) .

: Sending massive volumes of unsolicited emails.

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