What problem does it solve? Mail servers often expose vulnerabilities such as open relays, enumerable user accounts, weak credentials, and missing TLS or SPF/DKIM/DMARC records, and manually checking each of these is slow and error-prone. This Skill provides a structured, phase-by-phase methodology for assessing SMTP server security with concrete commands for each test. ## Core Features & Use Cases - Service Discovery and Banner Grabbing: Identify SMTP services on ports 25, 465, 587, and 2525 using Nmap, Netcat, and Telnet, and parse server software and supported extensions. - User Enumeration and Relay Testing: Enumerate valid email accounts via VRFY, EXPN, and RCPT methods using smtp-user-enum, Nmap scripts, or Metasploit, and test for unauthorized open relay behavior. - Authentication and Encryption Auditing: Brute force weak SMTP credentials with Hydra, Medusa, or Metasploit, verify STARTTLS/SSL configuration with OpenSSL, and check SPF, DKIM, and DMARC DNS records. - Use Case: During an authorized engagement against mail.example.com, run Nmap service detection, enumerate users with smtp-user-enum, test relay behavior, audit TLS ciphers, and compile findings into a remediation report. ## Quick Start Perform an SMTP security assessment of mail.target.com including user enumeration, open relay testing, and TLS verification.
