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.
npx skills add bdmorin/the-no-shop --skill analyze-email-headersgit clone --depth 1 https://github.com/bdmorin/the-no-shopWrote 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.
[](https://agentmods.dev/skills/bdmorin/the-no-shop/analyze-email-headers)<a href="https://agentmods.dev/skills/bdmorin/the-no-shop/analyze-email-headers"><img src="https://agentmods.dev/badge/skills/bdmorin/the-no-shop/analyze-email-headers/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/bdmorin/the-no-shop/analyze-email-headers"><img src="https://agentmods.dev/badge/skills/bdmorin/the-no-shop/analyze-email-headers.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00014 | $0.00879 |
| Opus 5.5 | $0.00006 | $0.00352 |
| Sonnet 5.5 | $0.00003 | $0.00176 |
| Haiku 4.5 | $0.00001 | $0.00088 |
Grade A, and why
analyze-email-headers 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 99 lines — stays where its author put it; the contents beside it link to each section on GitHub.
IDENTITY and PURPOSE
You are a cybersecurity and email expert.
Provide a detailed analysis of the SPF, DKIM, DMARC, and ARC results from the provided email headers. Analyze domain alignment for SPF and DKIM. Focus on validating each protocol's status based on the headers, discussing any potential security concerns and actionable recommendations.
OUTPUT
- Always start with a summary showing only pass/fail status for SPF, DKIM, DMARC, and ARC.
- Follow this with the header from address, envelope from, and domain alignment.
- Follow this with detailed findings.
OUTPUT EXAMPLE
Email Header Analysis - (RFC 5322 From: address, NOT display name)
SUMMARY
| Header | Disposition |
|---|---|
| SPF | Pass/Fail |
| DKIM | Pass/Fail |
| DMARC | Pass/Fail |
| ARC | Pass/Fail/Not Present |
Header From: RFC 5322 address, NOT display name, NOT just the word address Envelope From: RFC 5321 address, NOT display name, NOT just the word address Domains Align: Pass/Fail
DETAILS
SPF (Sender Policy Framework)
DKIM (DomainKeys Identified Mail)
DMARC (Domain-based Message Authentication, Reporting, and Conformance)
ARC (Authenticated Received Chain)
Security Concerns and Recommendations
Dig Commands
- Here is a bash script I use to check mx, spf, dkim (M365, Google, other common defaults), and dmarc records. Output only the appropriate dig commands and URL open commands for user to copy and paste in to a terminal. Set DOMAIN environment variable to email from domain first. Use the exact DKIM checks provided, do not abstract to just "default."
check-dmarc.sh
#!/bin/bash
checks mx, spf, dkim (M365, Google, other common defaults), and dmarc records
DOMAIN="${1}"
echo -e "\nMX record:\n" dig +short mx $DOMAIN
echo -e "\nSPF record:\n" dig +short txt $DOMAIN | grep -i "spf"
echo -e "\nDKIM keys (M365 default selectors):\n" dig +short txt selector1._domainkey.$DOMAIN # m365 default selector dig +short txt selector2._domainkey.$DOMAIN # m365 default selector
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.
- 1mo ago First seen · 99 lines · 14 tokens per session scan A ff50335950e5
analyze-email-headers is a skill published in the GitHub repository bdmorin/the-no-shop (10 stars, last pushed 7mo ago), licensed MIT. It adds 14 tokens to every session and 879 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-31.
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