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email-copywriting

Skill9 starsChanged 8 months agoMITView on GitHub

Write effective marketing emails with compelling subject lines, preview text, body copy, and CTAs. Use when writing email campaigns or sequences.

We split this skill into the rules it gives an agent

19 rules. 0 are common, 19 are distinctive, and 0 are very specific to this project.

  • 0

    Common

    Most of the 3 edited versions we read keep these.

  • 19

    Distinctive

    This author's own choices. Worth a look.

  • 0

    Very specific

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

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Use this skill when:

    line 11
  2. Distinctive:

    Before writing email copy, clarify:

    line 22
  3. Distinctive:

    One email, one goal: If the email has two CTAs pointing to different actions, pick one and remove the other.

    line 33
  4. Distinctive:

    Subject line > body copy > CTA: If the subject line fails, nothing else matters because no one reads the email.

    line 34
  5. Distinctive:

    Every sentence must earn the next sentence: If a line doesn't add value, cut it.

    line 37
  6. Distinctive:

    Create urgency: If the subject line is curiosity-based, the preview text adds urgency

    line 95
  7. Distinctive:

    Only personalize when it adds genuine value

    line 185
  8. Distinctive:

    Always set fallback text for missing data ("Hi there" if first name is blank)

    line 186
  9. Distinctive:

    Don't be creepy — using behavioral data is fine.

    line 187
  10. Distinctive:

    Test personalized vs non-personalized versions (personalization doesn't always win)

    line 188
  11. Distinctive:

    If you can say it in fewer words, do

    line 203
  12. Distinctive:

    Test short vs long versions of the same email — results vary by audience

    line 206
  13. Distinctive:

    Keep it to 1-2 sentences

    line 239
  14. Distinctive:

    Don't use P.S. in every email — it loses impact

    line 241
  15. Distinctive:

    Test ONE variable at a time

    line 257
  16. Distinctive:

    Run the test for at least 24 hours (preferably 48) before declaring a winner

    line 259
  17. Distinctive:

    Use open rate for subject line tests, click rate for body/CTA tests, conversion rate for offer tests

    line 260
  18. Distinctive:

    Document every test and its result — build an institutional testing playbook

    line 261
  19. Distinctive:

    Before finalizing any email copy:

    line 300

“Common” is measured: kept by at least 6 in 10 of the 3 edited versions of this file we could read. “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

Email Copywriting

When to Activate

Use this skill when:

  • Writing subject lines for email campaigns
  • Drafting email body copy (promotional, educational, transactional)
  • Optimizing CTAs and button copy
  • Writing email sequences (welcome, sales, nurture)
  • A/B testing email copy elements
  • Reviewing and improving existing email copy
  • Writing preview text and preheader copy

First Questions

Before writing email copy, clarify:

  1. What is the email's ONE goal? (Click, reply, purchase, register, read)
  2. Who is the recipient? (Segment, relationship stage, pain points)
  3. What action should the reader take after reading?
  4. What is the offer or value proposition?
  5. Is this a standalone campaign or part of a sequence? (Context from previous emails?)
  6. What tone/voice does the brand use? (Formal, conversational, edgy, warm)
  7. Is this plain text, HTML, or hybrid?

Core Rules

  1. One email, one goal. If the email has two CTAs pointing to different actions, pick one and remove the other.
  2. Subject line > body copy > CTA. If the subject line fails, nothing else matters because no one reads the email.
  3. Write for scanners. Most people scan emails in 3-8 seconds. Structure for scanning with headers, bold text, short paragraphs, and bullet points.
  4. Write like a human, not a brand. Emails that feel like letters from a person outperform corporate announcements.
  5. Every sentence must earn the next sentence. If a line doesn't add value, cut it.
  6. Mobile first. 60%+ of email opens are on mobile. Short subject lines, short paragraphs, large tappable buttons.
  7. The CTA must be unmissable. One primary CTA, above the fold, clear and action-oriented.

Subject Line Formulas

Curiosity-Driven

  1. "The [thing] that [unexpected result]"
  2. "Why [common practice] doesn't work anymore"
  3. "I was wrong about [topic]"
  4. "[First name], you're not going to believe this"
  5. "The secret behind [impressive result]"

Benefit-Driven

  1. "How to [achieve result] in [timeframe]"
  2. "[Number] ways to [solve problem] (without [common objection])"
  3. "The fastest way to [desired outcome]"
  4. "Get [specific result] — here's how"
  5. "Your [problem] ends today"

Urgency/Scarcity

  1. "[X] hours left: [offer summary]"
  2. "Last chance for [specific benefit]"
  3. "This closes tonight at midnight"
  4. "Only [number] spots left"
  5. "[First name], your [offer] expires soon"

Social Proof

  1. "How [customer name] achieved [result]"
  2. "Join [number] people who [action]"
  3. "The [thing] [industry leaders] swear by"
  4. "What [respected person/company] taught me about [topic]"

Personal/Conversational

  1. "Quick question, [first name]"
  2. "Can I be honest with you?"
  3. "I made a mistake"
  4. "This is for you (literally)"
  5. "You'll thank me later"

Subject Line Rules

  • Length: 30-50 characters (6-10 words). Under 40 characters performs best on mobile.
  • Front-load the compelling part. What's after character 40 gets truncated on mobile.
  • Avoid spam triggers: FREE, ACT NOW, !!!, ALL CAPS, $$$
  • Use personalization selectively. [First name] in subject lines increases open rates ~5-10% but loses impact if overused.
  • Lowercase can work. All-lowercase subject lines feel casual and personal: "hey, quick thought about your strategy"
  • Questions outperform statements (in most cases)
  • Numbers outperform words: "5 ways" beats "five ways"
  • Emojis: One emoji can lift opens 2-5% in B2C. Avoid in B2B. Never more than one.

Preview Text Optimization

Preview text (preheader) is the text that appears after the subject line in the inbox. It's your second chance to earn the open.

Best Practices

  • Length: 40-90 characters (complements, doesn't repeat, the subject line)
  • Extend the story: Subject line starts a thought, preview text continues it
  • Add context: What will the reader get from opening?
  • Create urgency: If the subject line is curiosity-based, the preview text adds urgency
  • Avoid default text: "View this email in your browser" or the first line of the email body

Preview Text Formula

Subject: [Curiosity or benefit hook]
Preview: [Context, additional benefit, or urgency that complements the subject]

Examples:

Subject: "The pricing mistake costing you customers"
Preview: "I see this in 90% of the businesses I audit."

Subject: "Your weekly marketing roundup"
Preview: "This week: a LinkedIn hack that tripled our reach."

Subject: "Last day: 30% off everything"
Preview: "Sale ends tonight at 11:59 PM. Here's what to grab."

Email Structure

The Inverted Pyramid

The most effective email structure narrows from broad to specific:

[ATTENTION] — Broad hook that connects to the reader's world
      |
[INTEREST] — Narrow to the specific topic/value
      |
[DESIRE] — Build the case for action (benefits, proof, urgency)
      |
[ACTION] — Single, clear CTA button

One-Column Layout

  • One column is the only reliable layout for mobile
  • Maximum width: 600px for the email body
  • Font size: 16px minimum for body text, 22-28px for headings
  • Line height: 1.5 for readability
  • Paragraph length: 1-3 sentences maximum

Structural Elements

  1. Opening line — Hook or connection to the reader's situation (1-2 sentences)
  2. Value body — The main content, broken into scannable chunks (3-5 short paragraphs or bullets)
  3. Transition to CTA — Bridge the value to the action ("Here's how to apply this...")
  4. CTA button — Single, clear, action-oriented button
  5. P.S. line — Optional but highly effective (see below)

CTA Button Copy

Rules for CTA Buttons

  • Action verb + benefit: "Get My Free Guide" not "Submit"
  • First person often wins: "Start My Trial" outperforms "Start Your Trial"
  • Specific over vague: "Download the 2025 Report" beats "Learn More"
  • One primary CTA per email. Secondary links are fine in text, but one button dominates.
  • Above the fold. The CTA should be visible without scrolling on mobile.
  • Repeat the CTA at the bottom of longer emails.

CTA Copy Examples

WeakStrong
SubmitGet My Free Checklist
Click HereSee the Results
Learn MoreShow Me How It Works
Buy NowStart Saving Today
Sign UpJoin 5,000+ Marketers
DownloadGrab Your Copy

Button Design

  • Minimum size: 44x44 px tap target (mobile-friendly)
  • High contrast color (stands out from the email background)
  • Rounded corners (tested to outperform sharp corners in many contexts)
  • Whitespace above and below the button (breathing room)

Personalization Techniques

Beyond First Name

TechniqueExampleData Required
Recent behavior"I noticed you checked out [product]..."Page visit tracking
Purchase history"Since you loved [Product A], you'll love..."Purchase data
Location"Marketing events near [city] this month"Location data
Company/role"As a [job title] at [company]..."CRM data
Engagement"You've been reading a lot about [topic]..."Email click data
Milestone"Congratulations on your 1-year anniversary with us!"Date tracking
Conditional contentShow different offers based on segmentSegment tags

Personalization Rules

  • Only personalize when it adds genuine value
  • Always set fallback text for missing data ("Hi there" if first name is blank)
  • Don't be creepy — using behavioral data is fine; making it feel like surveillance is not
  • Test personalized vs non-personalized versions (personalization doesn't always win)

Email Length by Purpose

Email TypeIdeal LengthReasoning
Promotional50-125 wordsQuick hit, fast action
Newsletter200-500 wordsCurated value, scannable
Educational300-600 wordsTeaching requires depth
Sales email150-300 wordsClear problem-solution-CTA
Welcome email100-200 wordsWarm, brief, set expectations
Re-engagement50-100 wordsShort, direct, low friction
TransactionalAs neededClarity over brevity

Length Rules

  • If you can say it in fewer words, do
  • Long emails work ONLY when every word earns its place
  • Break long emails into scannable sections (bolded headers, bullets, short paragraphs)
  • Test short vs long versions of the same email — results vary by audience

Plain Text vs HTML

When to Use Plain Text

  • Personal outreach (sales emails, founder emails)
  • Reply-based campaigns ("Hit reply and tell me...")
  • High-deliverability contexts (plain text has fewer spam filter triggers)
  • 1:1 communication style
  • B2B relationship-building emails

When to Use HTML

  • Product showcases (images are essential)
  • Newsletters with branded design
  • Promotional campaigns with visual CTAs
  • E-commerce (product images, pricing, buttons)
  • Any email where design supports comprehension

Hybrid Approach

Many marketers use "designed plain text" — HTML emails with minimal formatting that look like personal emails but have branded fonts, a logo, and styled CTA buttons. This combines the personal feel of plain text with the functionality of HTML.

The P.S. Line Technique

The P.S. line is one of the most-read elements of any email. Eye-tracking studies show readers often scan: subject line, first line, and P.S. before reading the body.

Uses for P.S.

  • Reinforce the CTA: "P.S. The early-bird price ends Friday. [Link]"
  • Add social proof: "P.S. 2,300 people have already signed up."
  • Create urgency: "P.S. Only 12 spots remaining."
  • Add a personal touch: "P.S. I wrote this while my daughter was napping. True story."
  • Introduce a secondary offer: "P.S. If this isn't for you, forward this to someone who needs it."

P.S. Rules

  • Keep it to 1-2 sentences
  • Include a link if it references an action
  • Don't use P.S. in every email — it loses impact
  • Make it feel like an afterthought (even though it's strategic)

A/B Testing Email Copy Elements

What to Test (In Priority Order)

  1. Subject lines — Highest impact on opens
  2. CTA copy and placement — Highest impact on clicks
  3. Email length — Short vs long versions
  4. Tone/voice — Formal vs casual
  5. Personalization — With vs without
  6. Send time — Morning vs afternoon, weekday vs weekend
  7. From name — Person vs brand name
  8. Preview text — Different angles

Testing Rules

  • Test ONE variable at a time
  • Minimum 1,000 recipients per variant (500 per group minimum)
  • Run the test for at least 24 hours (preferably 48) before declaring a winner
  • Use open rate for subject line tests, click rate for body/CTA tests, conversion rate for offer tests
  • Document every test and its result — build an institutional testing playbook
  • Statistical significance matters: aim for 95% confidence before acting on results

Testing Documentation Template

TEST: [What's being tested]
DATE: [Send date]
SAMPLE SIZE: [Total and per variant]
VARIANT A: [Description]
VARIANT B: [Description]
METRIC: [What's being measured]
RESULT: [Variant A: X% | Variant B: Y%]
WINNER: [A or B]
CONFIDENCE: [Statistical significance %]
INSIGHT: [What did we learn?]
NEXT TEST: [What will we test next based on this?]

Email Copywriting Checklist

Before Sending

  • Is there ONE clear goal for this email?
  • Is the subject line under 50 characters and compelling?
  • Does the preview text complement (not repeat) the subject line?
  • Is the opening line a hook, not a generic greeting?
  • Is the email scannable? (Short paragraphs, headers, bullets)
  • Is there ONE primary CTA that is unmissable?
  • Is the CTA above the fold on mobile?
  • Is the CTA button copy action-oriented and specific?
  • Is the email mobile-friendly? (One column, 16px+ font, tappable buttons)
  • Are personalization merge tags tested with fallbacks?
  • Is the tone consistent with the brand voice?
  • Has the email been proofread by a second pair of eyes?
  • Is the unsubscribe link present and functional?
  • Has the email been tested on Gmail, Outlook, and Apple Mail?
  • Would YOU open and read this email if it arrived in your inbox?

Quality Gate

Before finalizing any email copy:

  • Can you state the email's goal in one sentence?
  • Does the subject line create enough curiosity or promise enough value to earn an open?
  • Does the first line earn the second line?
  • Is every sentence necessary? (Cut anything that doesn't serve the goal)
  • Is the CTA crystal clear?
  • Has the copy been read aloud? (Catches awkward phrasing and robotic tone)
  • Is the email appropriate for the recipient's relationship stage? (Don't hard-sell a new subscriber)
  • Has at least one subject line A/B test been planned?

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