Email Sequence Skill

Subject Line Rules

• Keep between 30-50 characters (6-10 words).
• Front-load the most important word.
• Use lowercase for a casual feel, title case for professional.
• Never use ALL CAPS for the full subject line.
• Include personalization (first name) sparingly, not in every email.
• A/B test every subject line in your ESP.

Preview Text Rules

• Always write custom preview text (40-90 characters).
• Do not repeat the subject line.
• Complement the subject line by adding context or intrigue.
• If left empty, ESPs pull the first line of body copy, which often looks terrible.

Email Structure

1. Hook (first 2 lines) - Must earn the scroll. Ask a question, state a bold claim, or reference something personal.
2. Body (3-8 sentences) - One idea per email. Do not try to cover everything.
3. CTA (1 primary) - One clear action. Link it 2-3 times in the body.
4. PS line (optional) - Second-most-read part of an email. Use for urgency or bonus info.

Send Timing Guidelines

Segmentation Rules

Segment sequences based on:

• Behavior - Pages visited, features used, emails opened, links clicked.
• Demographics - Industry, company size, role, location.
• Lifecycle stage - New lead, trial user, paying customer, churned user.
• Engagement level - Active (opened in 30 days), Inactive (no opens in 60+ days).
• Source - How did they enter the sequence? Organic, paid, referral, event.

Sequence Templates

1. Welcome Series (5 Emails)

Goal: Introduce the brand, build trust, drive first conversion. Trigger: New email signup or account creation.

2. Abandoned Cart Series (3 Emails)

Goal: Recover abandoned purchases. Trigger: Cart created but checkout not completed within 1 hour.

3. Re-engagement Series (4 Emails)

Goal: Win back inactive subscribers before removing them. Trigger: No email opens or clicks in 60-90 days.

4. Product Launch Series (6 Emails)

Goal: Build anticipation and drive launch-day conversions. Trigger: Manual send based on launch timeline.

5. Onboarding Series (7 Emails)

Goal: Activate new users and drive them to their "aha moment." Trigger: New account creation or first purchase.

Email Copywriting Rules

Hook Formulas for Email Openings

Body Copy Rules

1. One idea per email. Do not try to educate, sell, and announce in the same email.
2. Short paragraphs. 1-3 sentences maximum. Emails are read on mobile.
3. Use "you" more than "we." Flip the ratio: 3:1 "you" to "we."
4. Write at a 5th-8th grade level. Short words, short sentences.
5. Link the CTA 2-3 times. Once in the middle, once at the end, optionally in a PS.
6. Use a PS line. 79% of readers scan the PS. Use it for urgency or a secondary point.

Spam Trigger Avoidance

Avoid these in subject lines and body:

• ALL CAPS words (e.g., "FREE", "BUY NOW", "CLICK HERE")
• Excessive exclamation marks (!!!)
• Spam trigger phrases: "Act now", "Limited time", "You've been selected", "Congratulations", "No obligation", "100% free", "Click below", "Dear friend"
• Too many images with too little text (maintain 60/40 text-to-image ratio)
• Deceptive subject lines (Re:, Fwd: when not actually a reply/forward)
• Purchased lists (always use opt-in subscribers only)

HTML Email Template Guidelines

When the user requests HTML email templates:

1. Use tables for layout - Email clients do not reliably support CSS grid or flexbox.
2. Inline all CSS - Many email clients strip <style> blocks.
3. Max width: 600px - Standard email width for cross-client compatibility.
4. Use web-safe fonts - Arial, Helvetica, Georgia, Times New Roman.
5. Include alt text on all images - Many readers have images disabled.
6. Test in multiple clients - Gmail, Outlook, Apple Mail, Yahoo at minimum.
7. Mobile-first - 60%+ of emails are opened on mobile. Stack columns on small screens.
8. Include a plain-text version - Always provide a text fallback for deliverability.

Sending Emails via Resend API

This skill can send emails directly using the Resend API. This is optional: if the API key is not configured, the skill will still generate email content as usual without sending.

Prerequisites

The RESEND_API_KEY environment variable must be set. Check for it by running:

source ~/.claude/.env.global 2>/dev/null
if [ -z "$RESEND_API_KEY" ]; then
  echo "RESEND_API_KEY is not set. Emails will be generated but not sent."
  echo "To enable sending, add RESEND_API_KEY to ~/.claude/.env.global"
else
  echo "RESEND_API_KEY is configured. Ready to send emails."
fi

Sending a Single Email

Use the Resend /emails endpoint to send an individual email from the sequence:

source ~/.claude/.env.global 2>/dev/null
curl -X POST https://api.resend.com/emails \
  -H "Authorization: Bearer ${RESEND_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "Your Name <[email protected]>",
    "to": ["[email protected]"],
    "subject": "Subject line here",
    "html": "<p>Email body here</p>"
  }'

The response returns a JSON object with an id field for tracking. Replace the from, to, subject, and html fields with the actual values from the generated sequence.

Sending a Batch (Full Sequence)

To send multiple emails from a sequence at once, use the batch endpoint. This is useful for sending the same email to multiple recipients or sending several sequence emails simultaneously:

source ~/.claude/.env.global 2>/dev/null
curl -X POST https://api.resend.com/emails/batch \
  -H "Authorization: Bearer ${RESEND_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "emails": [
      {
        "from": "Your Name <[email protected]>",
        "to": ["[email protected]"],
        "subject": "Email 1: Welcome to [Brand]",
        "html": "<p>Welcome email body</p>"
      },
      {
        "from": "Your Name <[email protected]>",
        "to": ["[email protected]"],
        "subject": "Email 1: Welcome to [Brand]",
        "html": "<p>Welcome email body</p>"
      }
    ]
  }'

Important Notes

• Domain verification required: The from address domain must be verified in your Resend account. If you have not verified a domain, Resend provides a shared [email protected] address for testing.
• Rate limits: Resend has rate limits depending on your plan. For large sequences, add a short delay between batch calls.
• No RESEND_API_KEY? The skill works without it. All email content (subject lines, body copy, preview text, timing) is generated normally. The Resend integration simply adds the ability to send the generated emails directly from the CLI.

Output Format

For every email sequence, deliver:

1. Sequence Overview

• Sequence name, goal, trigger, audience segment.
• Visual flow diagram (text-based).

2. Individual Emails

For each email in the sequence:

• Email number and name (e.g., "Email 3: Social Proof")
• Timing (delay from previous email or trigger)
• Subject line (primary + 2 A/B variants)
• Preview text
• From name and email
• Body copy (full draft, not an outline)
• CTA (text and URL placeholder)
• PS line (if applicable)
• Branch logic (if applicable: what happens if they open/click/don't)

3. Segmentation Rules

Who enters this sequence, who exits, and any branch conditions.

4. Success Metrics

Target open rates, click rates, and conversion rates for each email.

5. A/B Test Plan

Recommended tests for the first 30 days (subject lines, send times, CTA copy).