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performing-email-security-testing

Tests SMTP open relay, SPF/DKIM/DMARC bypass, and email header injection during authorized penetration tests.

954|172|Updated Mar 13, 2026
Search Tags:#penetration testing#SMTP#open relay#spf#dmarc#email security#header injection
One-click install
npx skills add https://github.com/xalgord/xalgorix --skill performing-email-security-testing
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: performing-email-security-testing
Source: https://github.com/xalgord/xalgorix/tree/main/internal/tools/skills/data/web-application-security/performing-email-security-testing
Command: npx skills add https://github.com/xalgord/xalgorix --skill performing-email-security-testing

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Email infrastructure is often misconfigured, allowing attackers to spoof domains, relay spam, or inject headers through web forms. This Skill provides a structured workflow to assess email security posture and prove vulnerabilities with delivered-message evidence rather than assumptions.

Core Features & Use Cases

  • Email Authentication Assessment: Enumerate and analyze SPF, DKIM, and DMARC records to identify spoofing weaknesses, then confirm with real spoofed-message delivery tests.
  • SMTP Open Relay and TLS Testing: Detect unauthenticated relaying on ports 25/465/587 and check STARTTLS enforcement against downgrade attacks.
  • Web Email Attack Surface Testing: Test contact forms for CRLF header injection and password reset flows for host header poisoning, token predictability, and user enumeration.
  • Use Case: During an authorized pentest, you discover the target has no DMARC record and SPF softfail. You send a spoofed email as [email protected] to your controlled test inbox, confirm delivery, and document a proven domain-spoofing finding.

Quick Start

Run an email security assessment against target.example.com covering MX enumeration, SPF/DKIM/DMARC analysis, open relay testing, and header injection checks.

Frequently Asked Questions about performing-email-security-testing

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I test if a domain is vulnerable to email spoofing?▼

Check the SPF record for softfail (~all) or missing records, and the DMARC record for p=none or absence. Then send a real spoofed message via swaks to a controlled inbox and inspect the received Authentication-Results headers to confirm delivery.

How to test for SMTP open relay with swaks?▼

Use swaks with an external MAIL FROM address and a controlled test recipient against the target mail server on ports 25, 465, or 587. A 250 OK response alone is not proof; confirm the message was actually delivered to your test inbox.

What is email header injection in contact forms?▼

Email header injection occurs when web form input containing CRLF sequences (%0d%0a) is passed unsanitized into mail headers, letting attackers add Bcc/Cc recipients or inject content. Confirm by checking whether an injected Bcc address receives the message.

Does a missing DMARC record mean spoofed emails will be delivered?▼

A missing DMARC record means no enforcement policy exists, so spoofed messages often reach inboxes, but delivery is not guaranteed. Always confirm by sending an actual spoofed email and reading the received Authentication-Results headers.

Why is an SMTP 250 OK response not proof of an open relay?▼

A 250 OK only means the server accepted the message; it may still be quarantined or silently dropped by downstream filters. True confirmation requires verifying the relayed message arrived in your controlled test inbox.

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