email-security

email-security is a skill for Claude Code, Codex from Miosa-osa/OSA. It costs 43 tokens per session (434 once invoked), scanned A, original, Apache-2.0.

An email-security guide for examining suspicious message headers and attachments without opening active content. It explains authentication checks such as SPF, DKIM, and DMARC, which help assess whether a sender is genuine.

In plain words
What is it for?
It helps triage phishing messages, review sender-authentication results, inspect attachments safely, and plan mail defenses.
Why use it?
It reduces the risk of opening dangerous content while investigating phishing and spoofed senders. It also helps turn email evidence into defensive steps.

Skill for Claude CodeCodex

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

Good fit It helps triage phishing messages, review sender-authentication results, inspect attachments safely, and plan mail defenses.

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Install with agentmods
npx agentmods add skills/miosa-osa/osa/email-security
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 Miosa-osa/OSA --skill email-security
Clone the repo
git clone --depth 1 https://github.com/Miosa-osa/OSA

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/miosa-osa/osa/email-security/github.svg)](https://agentmods.dev/skills/miosa-osa/osa/email-security)
Your own site
<a href="https://agentmods.dev/skills/miosa-osa/osa/email-security"><img src="https://agentmods.dev/badge/skills/miosa-osa/osa/email-security/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.

agentmods 80×15 button for email-security

Your own site · 80×15
<a href="https://agentmods.dev/skills/miosa-osa/osa/email-security"><img src="https://agentmods.dev/badge/skills/miosa-osa/osa/email-security.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 434 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.
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 $0.00043 $0.00434
Opus 5.5 $0.00017 $0.00174
Sonnet 5.5 $0.00009 $0.00087
Haiku 4.5 $0.00004 $0.00043

Measured 1mo ago against content hash e93d75fe9d27, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/headers.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

priv/skills/email-security/SKILL.md · 39 lines

What it actually says

Email Security

Workflow

  1. Preserve raw EML and hash; never follow links or render remote content during triage.
  2. Extract selected headers using the bundled parser. Read the worked example for trust boundaries.
  3. Identify the receiving organization's trusted authentication service before interpreting Authentication-Results. Attacker-supplied headers can lie.
  4. Compare visible sender, envelope identity, DKIM signing domain and documented alignment results; auth pass alone does not establish harmless content.
  5. Hash attachments without execution, record duplicate headers and parsing anomalies, and pass samples to sandbox-triage when needed.
  6. Propose narrow mail controls, test known good mail and the offending sample, and document rollback and delivery impact.

Worked example and prerequisites

Read references/workflow.md before execution. Use only registered OSA tools named in the frontmatter; command examples run through shell_execute. Check command -v for each external executable on the actual target. Optional packages, external collectors and vendor accounts are not bundled or presumed installed.

Evidence and completion

Return scope, prerequisites, exact checks, observed results, evidence paths, limitations, remediation, rollback and retest status. Mark unavailable checks as blocked or unverified. Preserve original evidence and report redacted copies where needed. Work within the authorized environment; do not silently expand to external targets.

Sources

Original OSA workflow and examples. Primary references are linked in the bundled workflow reference, so they remain available when this skill is installed separately. No third-party skill collection or rule pack is vendored.

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 1mo ago First seen · 39 lines · 43 tokens per session scan A e93d75fe9d27

Subscribe to this mod's changes

email-security is a skill published in the GitHub repository Miosa-osa/OSA (78 stars, last pushed 11d ago), licensed Apache-2.0. It adds 43 tokens to every session and 434 once invoked, about $0.0002 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 2026-09-15.