What An Email Reveals

Q: What is a Claude Code skill and how does the What An Email Reveals skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. What An Email Reveals is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Security · Sub-category: security-misc · Last updated: 2026-09-28

Investigate an email address — MX and syntactic validation, Gravatar lookup, corporate email-format inference, breach exposure, and full mail-header analysis covering the Received chain, Message-ID and SPF, DKIM and DMARC results. Use for email OSINT, verifying whether an address exists, finding accounts registered to it, guessing a company's email format, or tracing where a suspicious message actually came from. Applies to business email compromise and invoice-fraud investigation, phishing triage, vendor-payment verification, and pre-engagement research. Reference at useosint.com/skills/what-an-email-reveals.

Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

An email address is usually the highest-value selector in an investigation: it carries a name, a domain, an account history, and a breach footprint. The beginner error is trying to prove the address exists. Existence is the least interesting thing about it, it is the hardest thing to establish passively, and the techniques that establish it are the ones that expose you. Work the structure and the footprint first; treat validation as a bonus.

What this skill does

What An Email Reveals is a community-contributed Claude Code skill in the security-misc sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/what-an-email-reveals/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The What An Email Reveals Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 196,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/what-an-email-reveals
curl -L https://claudskills.com/skills/what-an-email-reveals/SKILL.md \
  -o ~/.claude/skills/what-an-email-reveals/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/what-an-email-reveals/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/what-an-email-reveals/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\what-an-email-reveals\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the What An Email Reveals Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/what-an-email-reveals/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the What An Email Reveals skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the What An Email Reveals skill?

Use What An Email Reveals when your Claude Code task falls under the Security category — specifically in the security misc area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use What An Email Reveals" or describe the task and let Claude pick). Browse related skills at /category/security/.

What is a Claude Code skill and how does the What An Email Reveals skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. What An Email Reveals is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/UseOSINT/Skills/blob/HEAD/skills/what-an-email-reveals/SKILL.md
License: MIT
Author: UseOSINT
Website: https://www.skills.sh/useosint/osint-skills

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

UseOSINT. (2026). What An Email Reveals [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/what-an-email-reveals/

BibTeX

@misc{what-an-email-reveals-2026,
  author    = {UseOSINT},
  title     = {What An Email Reveals [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/what-an-email-reveals/}
}

Embed this skill

Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →

Badge

[![ClaudSkills](https://claudskills.com/badge/what-an-email-reveals.svg)](https://claudskills.com/skills/what-an-email-reveals/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)

Security scan

Grade A · scanned 2026-09-28 — free static scan against the OWASP Agentic Skills Top 10.

The scan flagged 1 of 10 categories (filesystem), including lower-severity patterns. Patterns shown inside code fences are weighted as examples rather than instructions — read the grading methodology for what this does and does not guarantee.

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
⚠ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/what-an-email-reveals/#security)

More Security skills

Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Security skills → Top 100 skills

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