agentleFS
Sign inStart free
m-binimranm-binimran/marketing-pack/skills/subject-lines/SKILL.md

subject-lines

Skill1 starsChanged 5 months agoMITView on GitHub

Write email subject lines (and preview text) that get opens without tripping spam filters or misleading - with variations to A/B test. Use when finalizing an email or testing opens.

The file

We split this skill into the rules it gives an agent

3 rules. About 0 are common, 2 are distinctive, and 1 is very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈2

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 1

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    Deliverability: avoid spam-trigger words, ALL CAPS, and !!!

    line 16
  2. Distinctive:

    No deceptive subjects (law + trust).

    line 22
  3. Distinctive:

    Don't promise what the email doesn't deliver.

    line 23

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

subject-lines

The subject earns the open; the preview text closes it. Honest, specific, curiosity - not spam.

Process

  1. Angles to test: curiosity, benefit/outcome, specificity/number, question, personal/relevant, urgency (honest). Write 5-10 across angles.
  2. Keep it tight: front-load the point; mind mobile truncation (~40 chars shows).
  3. Preview text complements (doesn't repeat) the subject and extends the hook.
  4. Honesty: the subject must match the email's content (CAN-SPAM) - no fake "Re:"/"Fwd:" or false promises.
  5. Deliverability: avoid spam-trigger words, ALL CAPS, and !!! (spam-trigger-guard).

Output

  • A ranked set of subject-line options (+ preview text), labelled by angle, ready to A/B test.

Guardrails

  • No deceptive subjects (law + trust). No spammy formatting.
  • Don't promise what the email doesn't deliver.

Download now (ZIP)

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

No reviews yet

People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.

  • It worked
  • Partly
  • It didn't
What did you use it for? e.g. Reviewing pull requests in a Rails app

Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.

Check your setup, free