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Email Subject Lines

Organization
swan-gtm
email-subject-lines

Use this skill when you need a subject line for any email, want to improve open rates, or are A/B testing subject lines. Generates 5-10 high-converting email subject lines using 100 proven direct-response frameworks organized by psychological trigger (curiosity, urgency, pain point, authority, results, contrarian, value, action, empowerment, story, trend, quick win). Analyzes your email content to match the right frameworks, then outputs subject line variations with preview text recommendations. Trigger on "subject line", "email subject", "what should the subject be", "help with this email subject", "write subject lines", "improve my open rates", "subject line ideas", or any request involving email + subject line.

Overview

Publisherswan-gtm
Repositorygtm-skills
Skill nameemail-subject-lines
Stars
216
Forks
103
Bundled files
Instructions only
LicenseMIT
Links
  • Markdown instructions

    A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.

  • Works with any LLM

    AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.

  • Self-contained

    Everything the model needs lives in the instructions — no extra files to sync.

  • Open source

    Published by swan-gtm on GitHub. Read the source before you install it.

Installation

Install the Email Subject Lines AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

1

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

  1. Open the app and go to Plugins → Skills.
  2. Choose "Install from GitHub".
  3. Paste the skill folder URL below and confirm.
    https://github.com/swan-gtm/gtm-skills/tree/main/skills/daniel-bustamante/email-subject-lines
  4. Enable the skill in any chat where you want it available.
Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.
2

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills
git clone --depth 1 https://github.com/swan-gtm/gtm-skills.git /tmp/gtm-skills
mkdir -p .claude/skills
cp -r /tmp/gtm-skills/skills/daniel-bustamante/email-subject-lines .claude/skills/email-subject-lines
Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Email Subject Lines in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Email Subject Lines on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Email Subject Lines is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

  • Loaded only when it is needed

    The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.

  • Switch models mid-chat

    Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

Generate Email Subject Lines

Generate 5-10 high-converting subject lines for any email using 100 battle-tested frameworks from elite direct-response marketers — matched to your email's specific intent, emotion, and hook.


Why This Works

Subject lines are the most leveraged words you'll ever write. A 10% improvement in open rate on a 10,000-person list means 1,000 more people reading your email — from changing a few words. But most people write subject lines last, when they're tired, using whatever comes to mind first. This skill reverses that by matching your email's intent to proven psychological frameworks that have generated millions in revenue across thousands of campaigns. Every framework is categorized by trigger type so Claude picks the right ones for YOUR specific email.


How to Use This Skill

When triggered, ask the user for:

To generate subject lines, I need:

  1. Paste your email (or describe what it's about)
  2. Email type — Newsletter, promotional, welcome, launch, nurture, announcement?
  3. Audience tone — Casual/friendly, professional, edgy, motivational?
  4. Any words to avoid? — Overused phrases, brand restrictions, etc.

If the user just pastes an email without context, analyze it and generate subject lines immediately.


Process

Step 1: Analyze Email Intent

Read the email content and identify:

  • Primary goal: Sale, engagement, nurture, announcement, content delivery
  • Core emotion: Fear, curiosity, aspiration, frustration, excitement
  • Key hook elements: Numbers, results, pain points, authority figures, timeframes

Step 2: Match Frameworks

Select 3-5 framework categories that align with the email's intent:

Email IntentBest Framework Categories
Sales/promoUrgency, FOMO, Results, Value
EducationalCuriosity, Quick Win, Contrarian
Story-basedStory, Pain Point, Transformation
Authority-buildingAuthority, Social Proof, Results
Challenge/launchAction, Empowerment, Urgency
Newsletter/contentCuriosity, Value, Quick Win, Trend

Step 3: Generate 5-10 Subject Lines

For each, provide:

Subject line: [subject line]
Framework: [which framework it's based on]
Suggested preview text: [preview text that complements the subject line]

Style Rules

  • Keep under 50 characters when possible (mobile optimization)
  • Use specific numbers over vague claims
  • Match the sender's voice (casual vs. professional)
  • Lowercase often outperforms Title Case
  • Questions outperform statements for cold audiences
  • Specificity beats cleverness
  • One clear idea per subject line
  • Emojis: use sparingly, match sender's typical style
  • Avoid: "Unlock," "Discover," "Revolutionary," "Game-changing," "Don't miss"

Preview Text Guidelines

Preview text should:

  • Complement, not repeat the subject line
  • Add specificity or intrigue the subject line lacks
  • Be 40-90 characters (shows fully on mobile)
  • Create a 1-2 punch with the subject line
Subject Line StylePreview Text Approach
QuestionAnswer hint or amplify stakes
StatementAdd proof or specificity
Curiosity gapPartial reveal or benefit
UrgencyReinforce deadline or scarcity
Number-basedExpand on what's included

Framework Library (100 Frameworks by Trigger)

CURIOSITY TRIGGERS

  • The Is-It-Worth-It Formula: Is [popular tool/habit/strategy] a waste of time?
  • The Pattern Interrupt Question: What does your [mundane thing] say about [you/area]?
  • The Surprising Success Formula: [Impressive result]... without [expected requirement]?
  • The Celebrity Twist Hook: if [famous person] [did unexpected niche thing]
  • The Hidden Knowledge Hook: [Unexpected source] reveals the keys to [desired outcome]
  • The Weird Question Formula: What's the weirdest [niche thing] you've ever [action]?
  • The Earnings Curiosity Hook: How much [desired outcome] should you be [making] in [niche]?
  • The Inside Look Hook: Look inside [new resource] [format]
  • The High-Stakes Question Hook: What makes someone [desirable attribute]?

URGENCY & FOMO TRIGGERS

  • The FOMO Warning Formula: Ignore this and [negative consequence]
  • The Time-Sensitive Check-In: did your [new strategy] already [fail/break]?
  • The Obsolete Method Hook: Why traditional [industry/model] is dead
  • High-Stakes Decision Formula: Quitting on [big accomplishment]
  • Year-Start Preparation Formula: December starts, prepare the [new year] [area] [plan]

PAIN POINT TRIGGERS

  • The Rock Bottom Formula: Dealing with [emotionally vulnerable moment]
  • The Pain Point Reveal Hook: Your [thing] isn't [working]? Here's why
  • The Relatable Struggle Hook: Should I [stick to ideal behavior] or [give up]?
  • The "Invisible Mistake" Hook: The "invisible mistake" [crushing] your [desired outcome]
  • The Hidden Mistake Framework: Are your [common element] killing your [outcome]?
  • The Unspoken Reason Hook: The #1 reason [group] [experience negative situation]
  • Costly Niche Mistake Hook: [Common mistake] is costing you [valuable resource]
  • The "Why Everyone Struggles" Hook: Why so few [audience] get [desired outcome]
  • Common Niche Trap Formula: Why [common approach] fail (even mine)
  • The Wishful Thinking Formula: Still [risky behavior], hoping for the best?
  • Failure Stat Hook: [High number]% of [group] FAIL at [activity] because of this...

AUTHORITY & SOCIAL PROOF TRIGGERS

  • The Authority Name Drop Formula: [Well-known person] [did something with me] - here's what happened
  • The Insider Giveaway Hook: I [invested] [big number] in [authority] — here's everything I learned (for free)
  • The Niche Authority Hook: Learn [skill] from a [tangible credibility] expert
  • The Authority Challenge Hook: Sorry [famous person], but...
  • The Niche Poll Formula: XX [group] told me their biggest problem (do this to fix it)
  • Niche Audit Hook: I reviewed [big number] [assets], most made this critical mistake

RESULTS & SUCCESS TRIGGERS

  • The Short-Term Win Formula: My [X-month] journey to [milestone]
  • The "Instant Results" Formula: "This [tool] [delivered big outcome] in [short time]"
  • The Outlier Success Breakdown: How [thing] achieved [result] in [short timeframe] (not luck)
  • The Growth Snapshot Formula: [Month] [wins]: [number], [bigger number], [bigger number]
  • The Top Performer Breakdown: I tested [X] [tactics] – these [Y] made the most [result]
  • The ROI Revelation Hook: This [increased] my [metric] by [XX]%
  • The First Milestone Formula: How I [achieved] my first [milestone] as a [role]
  • The "Exact Path" Formula: Exactly what to do from [starting point] to [desired result]
  • The High ROI Investment Formula: He [achieved $result] from [low-cost tool]
  • The 10x Multiplier Formula: One change → [Big Result]
  • The Accidental Success Framework: The [$XX] accidental [strategy]

CONTRARIAN & REFRAME TRIGGERS

  • The Positive Reframe Hook: No, [outcome] doesn't have to [negative downside]
  • The "I Was Wrong" Hook: I was wrong about [popular idea]
  • The Dark Side Reveal Formula: The dark side of being [seemingly positive trait] (fixed)
  • The Hidden Cost Formula: The danger of being [seemingly good status]
  • The Unexpected Truth Formula: What if I told you [desired outcome] is not the goal?
  • The Contrarian Advice Formula: Most [topic] advice sucks
  • The "Success Despite" Framework: The [big outcome] built on [contrarian approach]
  • The Not-What-You-Think Formula: Your [thing people blame] may not be the problem
  • What-If Contrarian Strategy: What if [common habit] was the wrong move
  • Contrarian Advice Framework: Don't "[conventional advice]" in [New Year]
  • Paradoxical Success Formula: [Undesirable type] make the best [desirable type]

VALUE & RESOURCE TRIGGERS

  • The "Compressed Value" Formula: My [complex thing] broken down in 1 email
  • The Tangible Freebie Teaser: [Asset Type] [X] steps to [outcome]
  • The "Different Roads To Success" Hook: [number] ways to [achieve] [outcome]
  • The "Perfect Plan" Formula: Inside: Your perfect [resource] for [timeframe]
  • The Irresistible Freebie Formula: FREE [RESOURCE] [emoji]
  • The Niche Success Playbook Hook: The [dream outcome] [resource type]
  • The Anatomy Hook Framework: The anatomy of a [successful system]
  • Niche Playbook Formula: The [New Year] [Niche] Playbook
  • Quick Win Template Formula: This template makes [process] [improvement]
  • Hidden Gem Formula: The best [thing] you've never heard of
  • Timeless Secrets Formula: [Number] timeless secrets to [result]

ACTION & TRANSFORMATION TRIGGERS

  • The Do-This-Now Hook: If you're [archetype], [start] this new [thing]
  • The "Skip The Downside" Hook: [Desirable action] without [typical downside]
  • The "Stop/Start" Formula: Stop being a [current identity] and become a [powerful identity]
  • The Instant Upgrade Hook: [Watch/read] this to [achieve outcome]
  • The "Turn X Into Y" Formula: [X] ways to turn [strategy] into [outcome]
  • The Hate-to-Love Formula: how to stop hating [difficult but necessary thing]
  • The "Do-Or-Die" Hook: How to [result] (if your life depended on it...)
  • The Exit Strategy Framework: Why I quit [popular trend]
  • The Old Way Dilemma: still doing [action] the old way?
  • Yes-You-Can Formula: yes, you can [something unexpected or bold]

EMPOWERMENT & ENCOURAGEMENT TRIGGERS

  • The "Yes, You Can" Formula: Anyone can [achieve outcome] (yes, even you)
  • The Less-Is-More Hook: You don't need [common assumption]. Just [smaller thing].
  • The One Thing Framework: All successful [group] do this ONE single thing
  • The Challenge Acceptance Formula: [Negative situation]? GOOD
  • The Targeted Callout Hook: Only for [specific segment]...
  • The Implied Interest Hook: Because you're interested in [topic]

STORY & EXPERIENCE TRIGGERS

  • The "Miraculous Insight" Hook: [Struggle]—until something clicked.
  • The High-Stakes Failure Formula: My [big number] [topic] f*ck up
  • The Trial & Error Method: [X] [activities] later... [X] essential tips
  • The Love-Hate Formula: My love-hate relationship with [topic]
  • The Big Loss Curiosity Formula: [Big number] [people] [negative result]?
  • Unsuccessful Approach Breakdown: I [studied] one of the worst [subjects] ever

TREND & INNOVATION TRIGGERS

  • The Niche Tech Shift Hook: How [trend] is changing [industry] in [year]
  • The Niche Breakthrough Formula: How [brand] broke [platform] [timeframe]
  • The "Weird Works" Strategy: [X] simple (but weird) [culture] habits to [goal]
  • Unconventional Success Formula: Weird way to [get desirable outcome]

QUICK WIN TRIGGERS

  • The Little-Known Trick Hook: Hi, did you know [little-known hack]?
  • The Fast Win Formula: Quick ([additional benefit]) [niche] secret
  • The Equation Hook: 1 [change] = [better] [outcome]
  • The Quick Challenge Approach: [Short timeframe] [valuable outcome] challenge
  • The "Mini Rant" Hook: Mini rant: Bad ways to [achieve outcome]
  • The Overlooked Factor Hook: Why your [minor factor] matters more than ever
  • The "Facts Over Hype" Hook: The truth about [tactic or technique]
  • The Damn Good Framework: Damn, this is an A+ [advice, resource, thing]
  • The "Insert Here" Strategy: [Insert [common problem] here]
  • Cliche Disruptor Hook: Stop trying to [common advice] please

Quality Criteria

Each subject line must:

  • Be under 50 characters when possible (show fully on mobile)
  • Create a clear reason to open — curiosity, urgency, value, or emotion
  • Match the email's actual content — No clickbait that doesn't deliver
  • Sound human — Like something a real person would text a friend, not a marketing department
  • Be diverse — The batch should use different frameworks, not 5 variations of the same angle

What good looks like

A great batch of subject lines stays under 50 characters wherever possible so every line shows fully on mobile, and each one gives a clear reason to open — curiosity, urgency, value, or emotion. Every line matches the email's actual content; no clickbait that doesn't deliver. The lines sound human, like something a real person would text a friend rather than something from a marketing department, favoring specificity over cleverness with one clear idea per line. And the batch is diverse — different frameworks and psychological angles, not five variations of the same hook — each paired with preview text that complements rather than repeats the subject line.

Frequently asked questions

What does the Email Subject Lines AI skill do?

Use this skill when you need a subject line for any email, want to improve open rates, or are A/B testing subject lines. Generates 5-10 high-converting email subject lines using 100 proven direct-response frameworks organized by psychological trigger (curiosity, urgency, pain point, authority, results, contrarian, value, action, empowerment, story, trend, quick win). Analyzes your email content to match the right frameworks, then outputs subject line variations with preview text recommendations. Trigger on "subject line", "email subject", "what should the subject be", "help with this email...

Why use Email Subject Lines on TypingMind?

Because you install it once and use it with any model. Email Subject Lines is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Email Subject Lines in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/swan-gtm/gtm-skills/tree/main/skills/daniel-bustamante/email-subject-lines. TypingMind reads its SKILL.md and installs it as a skill you can enable per chat.

Which AI models can use Email Subject Lines?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Email Subject Lines?

As many as you like. As long as a model supports skills, you can use Email Subject Lines with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Email Subject Lines AI skill free?

Yes. It is published on GitHub by swan-gtm under the MIT license. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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