What security tools does this skill require?

The skill utilizes standard security tools including Nmap, Netcat, Hydra, smtp-user-enum, and the Metasploit Framework.

Can this skill detect open mail relays?

Yes, it includes specific workflows for testing and documenting unauthorized email relaying vulnerabilities using both manual and automated methods.

Is user enumeration possible with this skill?

Absolutely. It covers multiple enumeration methods including VRFY, EXPN, and RCPT TO logic to identify valid email accounts on a target server.

What is the SMTP Penetration Testing skill for Claude Code?

It is a specialized skill that provides Claude with a comprehensive framework for auditing SMTP servers, identifying vulnerabilities, and suggesting remediation steps.

Does it support testing for email spoofing protections?

Yes, it provides guidance on analyzing SPF, DKIM, and DMARC DNS records to ensure modern email authentication is correctly implemented.

SMTP Penetration Testing

Name: SMTP Penetration Testing
Author: zebbern

byzebbern

•

2,883

Security & Testing

Conducts comprehensive security audits of SMTP servers to identify vulnerabilities like open relays, user enumeration, and weak authentication.

About

This skill provides Claude with advanced capabilities for assessing the security posture of Mail Transfer Agents (MTAs) and email infrastructure. It guides users through systematic phases of SMTP testing, including service discovery, banner grabbing, command enumeration, and brute-force authentication. By integrating industry-standard tools and best practices, it helps security professionals and system administrators identify misconfigurations that could lead to email spoofing, unauthorized relaying, or credential compromise, while providing actionable remediation advice to harden mail servers.

Key Features

Automated SMTP service discovery and version detection using Nmap and Netcat
2,883 GitHub stars
Comprehensive user enumeration techniques via VRFY, EXPN, and RCPT TO commands
Detailed open relay testing and exploitation verification workflows
Security analysis for TLS/SSL configurations and SPF/DKIM/DMARC records
Authentication security assessment through automated brute-force patterns

Use Cases

Hardening SMTP servers against unauthorized email relaying and spam exploitation
Conducting professional network penetration tests on corporate mail infrastructure
Auditing email authentication protocols to prevent domain spoofing and phishing

About

Key Features

Automated SMTP service discovery and version detection using Nmap and Netcat
2,883 GitHub stars
Comprehensive user enumeration techniques via VRFY, EXPN, and RCPT TO commands
Detailed open relay testing and exploitation verification workflows
Security analysis for TLS/SSL configurations and SPF/DKIM/DMARC records
Authentication security assessment through automated brute-force patterns

Use Cases

Hardening SMTP servers against unauthorized email relaying and spam exploitation
Conducting professional network penetration tests on corporate mail infrastructure
Auditing email authentication protocols to prevent domain spoofing and phishing