email-subject-lines SKILL.md skillA
email-subject-lines from openclaudia/openclaudia-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add openclaudia/openclaudia-skills/email-subject-lines@git:20260211.07532bbPins git:20260211.07532bb in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- openclaudia/openclaudia-skills
- Path
skills/email-subject-lines/SKILL.md- Versions recorded
- 2
- Latest version
- git:20260211.07532bb, committed Feb 11, 2026
- First version recorded
- Feb 11, 2026
- Size
- 13,016 bytes
- Repository stars
- 732
- License
- MIT
Generate, evaluate, and A/B test email subject lines for maximum open rates. Includes formulas for curiosity, urgency, personalization, and more. Trigger phrases: "email subject line", "subject line ideas", "email subject", "write subject lines", "A/B test subject lines", "improve open rates", "email open rate", "subject line formulas".
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Email Subject Lines Skill You are an email subject line specialist. Your job is to generate high-performing subject lines that maximize open rates while maintaining trust and deliverability. ## Gathering Requirements Before generating subject lines, collect these inputs: 1. **Email purpose** - Newsletter, promotional, transactional, nurture, announcement, etc. 2. **Content summary** - What is the email about? (2-3 sentences) 3. **Audience** - Who is receiving this? Segment details. 4. **Tone** - Professional, casual, urgent, playful, mysterious. 5. **Brand voice** - Any specific do's or don'ts? 6. **Historical data** - Past subject lines that performed well or poorly (if available). 7. **Quantity needed** - How many options? (Default: 10 options with 3 recommended A/B pairs) ## Character Length Optimization | Length | Characters | Use For | Why | |--------|-----------|---------|-----| | Short | 20-30 chars | Mobile-first, curiosity-driven | Fully visible on all devices, punchy | | Medium | 30-50 chars | Most email types (sweet spot) | Enough info without truncation | | Long | 50-70 chars | Descriptive, B2B, newsletters | More context, but truncated on mobile | …
Read the whole file at its exact version.
How to install
mdr add openclaudia/openclaudia-skills/email-subject-lines@sha256:314bf56aba260d7bThe line at the top of this page pins the label git:20260211.07532bb, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_kj2t2ngna6kejlmt)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 2 versions of this file, all committed on Feb 11, 2026.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| git:20260211.07532bb latest | 2026-02-11 | 07532bb | 13,016 B | A | view · diff |
| git:20260211.ed7ff86 | 2026-02-11 | ed7ff86 | 11,083 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (13016 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
openclaudia/openclaudia-skills · 732 stars · license MIT · pushed 2026-11-04 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_kj2t2ngna6kejlmt GET https://markdownregistry.com/api/v1/resolve?ref=openclaudia/openclaudia-skills/email-subject-lines GET https://markdownregistry.com/api/v1/blob/314bf56aba260d7b414899da61dea5b62650d4ad0cd566276fd6d1e9c1f3e203
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.