md-to-eml

md-to-eml is a skill for Claude Code, Codex from fabioc-aloha/Alex_Skill_Mall. It costs 23 tokens per session (1,730 once invoked), scanned A, original, MIT.

A converter that turns Markdown with YAML frontmatter into RFC 5322 email files, using HTML formatting, inline CSS, and embedded images. An .eml file can be opened in email clients such as Outlook or Thunderbird.

In plain words
What is it for?
Create newsletters, governance messages, stakeholder updates, email templates, and test emails with links, tables, code, charts, or diagrams.
Why use it?
It lets teams review and distribute consistently formatted email from content maintained in Markdown.

Skill for Claude CodeCodex

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

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is node .github/muscles/md-to-eml.cjs newsletter.md.

Good fit Create newsletters, governance messages, stakeholder updates, email templates, and test emails with links, tables, code, charts, or diagrams.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/fabioc-aloha/Alex_Skill_Mall
agentmods
npx agentmods add skills/fabioc-aloha/alex_skill_mall/md-to-eml

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 md-to-eml

README.md
[![agentmods](https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/md-to-eml/github.svg)](https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/md-to-eml)
Your own site
<a href="https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/md-to-eml"><img src="https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/md-to-eml/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 md-to-eml

Your own site · 80×15
<a href="https://agentmods.dev/skills/fabioc-aloha/alex_skill_mall/md-to-eml"><img src="https://agentmods.dev/badge/skills/fabioc-aloha/alex_skill_mall/md-to-eml.svg" alt="Reviewed on agentmods" width="80" 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 1,730 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 $0.00023 $0.01730
Opus 5 $0.00012 $0.00865
Sonnet 5 $0.00005 $0.00346
Haiku 4.5 $0.00002 $0.00173

Measured 8d ago against content hash 67d17d6188a4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

md-to-eml 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 8d 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.

plugins/converters/md-to-eml/skills/md-to-eml/SKILL.md · 222 lines

How it starts

The opening of the file, as written. The whole thing — 222 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Markdown to Email Conversion

Write in Markdown, send as professional email — works in any email client

Staleness Watch: Recheck external API and tool URLs before release or after upstream changes.

Convert Markdown documents with YAML frontmatter into RFC 5322-compliant .eml files ready for governance, newsletter, and stakeholder communication workflows.


When to Use

  • Sending formatted content via email clients (Outlook, Thunderbird, etc.)
  • Newsletter or governance communication from Markdown sources
  • Generating test emails for review before batch sending
  • Converting documentation into distributable email format
  • Creating email templates with consistent branding
  • Stakeholder updates with embedded charts or diagrams

Supported Formatting

Format Status Notes
Headings H1-H6 with inline styles
Bold/Italic Standard emphasis
Links Clickable hyperlinks
Images CID embedded as attachments
Code blocks Monospace, gray background
Inline code Highlighted
Tables HTML tables with borders
Blockquotes Indented with border
Lists Ordered and unordered
Mermaid diagrams ⚠️ Table fallback (no JS in email)
Emoji Unicode preserved
Horizontal rules Styled dividers

Key Features

Feature Details
YAML frontmatter Maps to RFC 5322 headers (To, From, Subject, CC, Reply-To)
Email-safe HTML Inline CSS with table-based layout (no <style> blocks)
Mermaid fallback Diagrams converted to ASCII table representation (email-safe)
CID images Local images embedded as base64 multipart MIME attachments
Emoji preservation Subject and body emoji render correctly across clients
Test mode --test flag overrides recipients for safe preview

Usage

# Basic conversion
node .github/muscles/md-to-eml.cjs newsletter.md

# With test recipient override (safe preview)
node .github/muscles/md-to-eml.cjs newsletter.md --test --test-to [email protected]

# Embed images as CID attachments
node .github/muscles/md-to-eml.cjs update.md --inline-images

# Debug mode (saves intermediate HTML)
node .github/muscles/md-to-eml.cjs update.md --debug

Read the full file on GitHub · 222 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. 8d ago First seen · 222 lines · 23 tokens per session scan A 67d17d6188a4

Subscribe to this mod's changes

md-to-eml is a skill published in the GitHub repository fabioc-aloha/Alex_Skill_Mall (4 stars, last pushed yesterday), licensed MIT. It adds 23 tokens to every session and 1,730 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 2026-09-03.

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