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Email Marketing

Email marketing remains one of the highest-ROI channels in digital marketing (average $36 for every $1 spent). Effective email marketing is not about sending more emails - it is about sending the right message to the right person at the right time. This skill covers campaign design, drip sequence architecture, deliverability fundamentals, segmentation models, and systematic A/B testing.

When to use this skill

Trigger this skill when the user:

• Wants to design or improve an email campaign (newsletter, promotional, announcement)
• Needs to build a drip sequence (welcome series, onboarding, nurture, re-engagement)
• Asks about email deliverability, spam scores, or inbox placement
• Wants to write or improve subject lines or preview text
• Needs to set up email automation flows and triggers
• Asks about audience segmentation strategies
• Wants to run A/B tests on email content or timing
• Needs to understand or improve open rates, CTR, or conversion rates
• Asks about responsive / mobile email design
• Wants to set up lifecycle email automation

Do NOT trigger this skill for:

• SMS or push notification marketing (different channel mechanics)
• Cold outbound sales prospecting (governed by separate compliance frameworks like CAN-SPAM / GDPR and different deliverability rules than permission email)

Key principles

1. Permission-based always - Only email people who explicitly opted in. Purchased lists destroy sender reputation, violate GDPR/CAN-SPAM, and produce near-zero ROI. A small engaged list beats a large unengaged one every time.

2. Segment before sending - A single blast to your entire list is almost never the right move. Even basic segmentation (active vs. dormant, product interest, lifecycle stage) meaningfully improves relevance and reduces unsubscribes.

3. Subject line is 80% of the battle - If the email is not opened it does not exist. Spend disproportionate effort on subject lines and preview text. Test them constantly.

4. Mobile-first design - More than 60% of emails are opened on mobile. Single-column layouts, minimum 16px body text, large tap targets (44px+), and short subject lines (under 40 characters) are non-negotiable defaults.

5. Test everything - Intuition about what works in email is frequently wrong. Run structured A/B tests on subject lines, CTAs, send times, and content format. Let data override opinion.

Core concepts

Email types

Transactional emails have the highest open rates (60-80%) and must not be used for marketing purposes - doing so violates trust and often CAN-SPAM.

Deliverability factors

Deliverability is whether your email reaches the inbox (not just whether it was "sent"). Key factors:

Sender reputation - ISPs score your sending domain and IP based on engagement, spam complaints, and bounce rates. Reputation takes months to build and days to destroy. Keep complaint rates below 0.1% and hard bounce rates below 2%.

Authentication - Three DNS records that ISPs use to verify you are who you say you are:

• SPF (Sender Policy Framework) - lists authorized sending IPs for your domain
• DKIM (DomainKeys Identified Mail) - cryptographically signs each email
• DMARC (Domain-based Message Authentication) - policy for handling failures; start with p=none (monitor), progress to p=quarantine, then p=reject

List hygiene - Remove hard bounces immediately. Suppress unsubscribes immediately. Run re-engagement campaigns before sunsetting inactive subscribers.

Engagement signals - Opens, clicks, and replies positively signal to ISPs. Low engagement from a segment drags down your domain reputation. Suppress chronically unengaged subscribers.

Segmentation models

Key metrics

Note: Apple Mail Privacy Protection (MPP) inflates open rates since iOS 15. Use CTOR and conversion rate as more reliable engagement signals.

Common tasks

Design a drip sequence

A drip sequence is a series of pre-written emails sent on a schedule or triggered by behavior. Plan before writing:

1. Define the goal - What behavior should the sequence drive? (activation, purchase, re-engagement, education)
2. Map the journey - What does the subscriber need to know / feel / do at each step to move toward the goal?
3. Set timing - Welcome: immediate. Onboarding: days 0, 2, 5, 10. Nurture: weekly or bi-weekly. Re-engagement: day 30, 45, 60 of inactivity.
4. Write each email as a unit - Each email should have one goal, one CTA.

Ready-to-use templates for welcome, onboarding, and nurture sequences: see references/drip-templates.md.

Welcome series structure (3 emails):

• Email 1 (immediate): Deliver the promised value, set expectations, introduce brand
• Email 2 (day 2-3): Share your best piece of content or biggest benefit
• Email 3 (day 5-7): Social proof + primary CTA

Onboarding series structure (5 emails):

• Email 1 (day 0): Account created - first action to take (one thing only)
• Email 2 (day 2): How to accomplish the primary use case
• Email 3 (day 5): Advanced tip or power feature
• Email 4 (day 10): Success story from a similar user
• Email 5 (day 14): Check-in - did they reach activation? If not, offer help.

Nurture series structure:

• Value-first ratio: 3 educational emails for every 1 promotional email
• Frequency: 1-2 per week maximum; let engagement guide cadence
• Personalize based on content topic interest or product category

Write high-converting subject lines

Subject lines determine whether the email gets opened. Apply these formulas:

Subject line rules:

• Keep under 50 characters (under 30 for mobile previews)
• Avoid ALL CAPS, excessive punctuation, and spam trigger words (free!!!, act now)
• Preview text is the second subject line - write it intentionally (120-150 chars)
• Never deceive - a misleading subject line increases complaints and unsubscribes
• A/B test every subject line on a 20% sample before sending to full list

Build email segmentation strategy

1. Audit existing data - What do you actually have? (email, name, signup source, purchase history, behavioral events, custom attributes)
2. Define your segments - Start with 3-5 meaningful segments, not 20 micro-segments
3. Map content to segments - What does each segment need from you?
4. Set up suppression rules - Who should never receive this campaign type?
5. Plan re-entry criteria - When does someone move from one segment to another?

Minimum viable segmentation for most businesses:

• Active subscribers (opened or clicked in last 90 days)
• At-risk subscribers (no engagement in 90-180 days)
• Dormant subscribers (no engagement 180+ days) - run re-engagement or suppress

A/B test email campaigns

Test one variable at a time. Common elements to test in priority order:

A/B test process:

1. Form a hypothesis: "Personalized subject lines will increase open rate by 5%"
2. Split list randomly (not by time - that introduces bias)
3. Send simultaneously or within a 1-hour window
4. Wait for statistical significance (95% confidence, typically 24-48h)
5. Document result in a test log; apply winner to full list
6. Apply learning to future tests

Improve deliverability

Step 1 - Authenticate your domain (critical baseline):

# SPF record (TXT record on your domain)
v=spf1 include:sendgrid.net include:mailchimp.com ~all

# DKIM - generated by your ESP, looks like:
mail._domainkey.yourdomain.com TXT "v=DKIM1; k=rsa; p=<public-key>"

# DMARC record
_dmarc.yourdomain.com TXT "v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com"

Progress DMARC policy from p=none to p=quarantine to p=reject over 60-90 days as you verify all legitimate sending sources are authenticated.

Step 2 - Warm up new sending IPs:

• Week 1: 200-500 emails/day to your most engaged subscribers
• Week 2: 1,000-2,000/day
• Week 3-4: Double weekly until at target volume
• Never jump more than 2x volume day-over-day

Step 3 - Maintain list hygiene:

• Remove hard bounces immediately after every send
• Suppress unsubscribes within 10 business days (CAN-SPAM) / immediately (GDPR)
• Sunset subscribers with zero engagement after 6-12 months
• Use double opt-in to improve list quality at source

Step 4 - Monitor reputation:

• Google Postmaster Tools - monitor spam rate and domain reputation
• Microsoft SNDS - equivalent for Outlook/Hotmail
• MXToolbox - check blacklist status

Design responsive email templates

Email clients are fragmented - Outlook uses a Word rendering engine; Gmail clips emails over 102KB. Design for the lowest common denominator.

HTML email best practices:

• Use table-based layouts for maximum compatibility (CSS grid/flexbox fail in Outlook)
• Inline all CSS - many clients strip <style> blocks
• Single-column layout, 600px max width
• 16px minimum body font size; 22px+ for headlines
• Preheader text in a hidden <div> immediately after <body>
• Always include a plain-text version
• Images must have alt text; emails must render acceptably with images off
• CTA buttons built with HTML/CSS, not images
• Test in Litmus or Email on Acid before sending

Mobile-specific rules:

• Tap targets minimum 44x44px
• Short subject lines (under 30 chars show on most lock screens)
• Stack multi-column layouts to single column on mobile via media query
• Use system fonts (Arial, Georgia, Verdana) as fallbacks

Set up lifecycle email automation

Lifecycle automation sends the right message triggered by user behavior, not a calendar.

Core triggers and flows:

Automation setup checklist:

1. Define entry trigger (event, date, list membership change)
2. Set enrollment conditions (prevent duplicate enrollment)
3. Map the email sequence with delays
4. Set exit criteria (purchased, unsubscribed, became customer)
5. Add goal tracking to measure conversion
6. Review and prune flows quarterly

Anti-patterns / common mistakes

References

For detailed templates and ready-to-use content, read:

• references/drip-templates.md - Complete drip sequence templates for welcome, onboarding, nurture, and re-engagement flows

Only load the references file when the current task requires ready-to-use template content or detailed sequence copy.

Related skills

When this skill is activated, check if the following companion skills are installed. For any that are missing, mention them to the user and offer to install before proceeding with the task. Example: "I notice you don't have [skill] installed yet - it pairs well with this skill. Want me to install it?"

• email-deliverability - Optimizing email deliverability, sender reputation, or authentication.
• copywriting - Writing headlines, landing page copy, CTAs, email subject lines, or persuasive content.
• growth-hacking - Designing viral loops, building referral programs, optimizing activation funnels, or improving retention.
• content-marketing - Creating content strategy, writing SEO-optimized blog posts, planning content calendars,...

Install a companion: npx skills add AbsolutelySkilled/AbsolutelySkilled --skill <name>