The penalties for sending spam can be severe and vary by jurisdiction. Under the CAN-SPAM Act, violators can face fines of up to $43,792 per email. In the European Union, the GDPR imposes fines that can reach up to €20 million or 4% of the sender's annual global turnover, whichever is higher. These penalties underscore the importance of adhering to best practices and legal requirements in email marketing.