email-security

email-security is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 23 tokens per session (866 once invoked), scanned A, original, MIT.

A set of checks for email-domain protections: SPF, DKIM, and DMARC, which help control who may send email for a domain and how forged messages are handled.

In plain words
What is it for?
Use it during domain security checks to inspect sender policies, email signatures, DMARC enforcement, mail servers, and basic SMTP exposure.
Why use it?
It reveals whether attackers could impersonate a domain in phishing or business-email scams and explains what the DNS settings mean.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it during domain security checks to inspect sender policies, email signatures, DMARC enforcement, mail servers, and basic SMTP exposure.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/uphiago/recon-skills/email-security
About the project

Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.

uphiago/recon-skills · 1,247 stars · on GitHub · hiago.sh

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add uphiago/recon-skills --skill email-security
Clone the repo
git clone --depth 1 https://github.com/uphiago/recon-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for email-security

README.md
[![agentmods](https://agentmods.dev/badge/skills/uphiago/recon-skills/email-security.svg)](https://agentmods.dev/skills/uphiago/recon-skills/email-security)
Your own site
<a href="https://agentmods.dev/skills/uphiago/recon-skills/email-security"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/email-security.svg" alt="Measured on agentmods" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 866 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00023 $0.00866
Opus 5 $0.00012 $0.00433
Sonnet 5 $0.00005 $0.00173
Haiku 4.5 $0.00002 $0.00087

Measured 9d ago against content hash 007ff95a4fc3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

email-security scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

recon/email-security/SKILL.md · 101 lines

How it starts

The opening of the file, as written. The whole thing — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Email Security -- DMARC, SPF, DKIM

When to Use

  • During passive reconnaissance (Phase 1)
  • After initial DNS enumeration
  • DMARC p=none means the domain can be totally spoofed
  • Critical for identifying phishing/business email compromise risks

DMARC/SPF/DKIM Check Commands

# SPF
dig +short TXT $target | grep "v=spf1"

# DMARC
dig +short TXT _dmarc.$target

# DKIM (common selector: google)
dig +short TXT google._domainkey.$target

# MX
dig +short MX $target

Interpreting Results

Config Meaning Risk
v=spf1 ~all (softfail) SPF suggests blocking but doesnt enforce Spoofed emails may pass
v=spf1 ?all (neutral) SPF does nothing Totally permissive
v=spf1 include:amazonses.com ~all SES can send as domain Any AWS SES account can spoof
v=DMARC1; p=none DMARC disabled Zero spoofing protection
v=DMARC1; p=quarantine Failed emails go to spam Partial protection
v=DMARC1; p=reject Failed emails rejected Full protection
DKIM missing No cryptographic signature Email can be forged

Email Spoofing via SMTP

# Test SMTP relay
timeout 3 bash -c 'exec 3<>/dev/tcp/TARGET/25; head -1 <&3'

# Send spoofed email via open relay (swaks)
swaks --to [email protected] --from [email protected]   --server TARGET --body "Spoofed email"

Headers That Indicate Security Level

Header Value Meaning
Authentication-Results spf=pass SPF passed
Authentication-Results spf=fail SPF failed
Authentication-Results dmarc=pass DMARC passed
Authentication-Results dmarc=fail DMARC failed
Authentication-Results dkim=pass DKIM passed
Received-SPF Pass Sender authorized
Received-SPF Softfail Sender not fully authorized
Received-SPF Fail Sender not authorized
ARC-Authentication-Results Authentication chain

AWS SES Spoofing (When SPF includes amazonses.com)

With v=spf1 include:amazonses.com ~all:

  1. Create AWS account
  2. Configure SES with your own domain (verified)
  3. Send email with From: [email protected]
  4. SPF PASSES (because of include:amazonses.com)
  5. DMARC p=none -- provider delivers normally

Read the full file on GitHub · 101 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 101 lines · 23 tokens per session scan A 007ff95a4fc3

Subscribe to this mod's changes

email-security is a skill published in the GitHub repository uphiago/recon-skills (1,247 stars, last pushed 7d ago), licensed MIT. It adds 23 tokens to every session and 866 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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