- Change default use_tls from True to False to match typical STARTTLS setup - Add MailDeliveryError exception for mail delivery failures - Wrap send_mail calls in try-catch blocks to handle errors gracefully - Return 502 status code with error details when mail delivery fails - Add SMTP security mode selector in frontend (STARTTLS/TLS/None) - Add test mail form to admin panel - Handle empty SMTP credentials properly in update_mail_settings - Catch