Your MTA accepts the DEBUG mode. This mode is dangerous as it allows remote users to execute arbitrary commands as root without the need to log in.
Upgrade your MTA.
- Ipswitch IMail Server Multiple Local Privilege Escalation Vulnerabilities
- McAfee GroupShield for Exchange X-Header Security Bypass Vulnerability
- CMailServer ActiveX Control Multiple Buffer Overflow Vulnerabilities
- Sendmail 8.8.8 to 8.12.7 Double Pipe Access Validation Vulnerability
- Mail relaying (thorough test)