Deliverability Foundations

• Authenticate all sending domains: SPF, DKIM, and DMARC — missing any one tanks deliverability
• Warm up new domains/IPs: start with 50-100 emails/day, increase 20% daily over 2-4 weeks
• Never buy email lists — purchased lists destroy sender reputation permanently
• Clean list regularly: remove bounces immediately, unengaged after 90 days
• Monitor blacklists: MXToolbox, Google Postmaster Tools — problems compound if not caught early

List Health Metrics

• One spam complaint per 1000 emails is the danger zone — above this, inbox placement drops sharply

Subject Lines

• 40-50 characters optimal — truncates on mobile after 35-40
• Personalization works: name or company in subject increases opens 10-20%
• Curiosity beats clarity for opens, but clarity wins for clicks — balance based on goal
• Avoid spam triggers: ALL CAPS, excessive punctuation!!!, "free", "act now"
• Test emoji: works for some audiences, hurts others — A/B test before committing
• Preview text is second subject line — don't waste it with "View in browser"

Email Sequences

Welcome sequence (5-7 emails over 2 weeks):

• Immediate: Deliver promised value + set expectations
• Day 1: Best content or quick win
• Day 3: Story/origin + values
• Day 5: Social proof + case study
• Day 7: Soft offer or deeper engagement
• Day 10: Address common objection
• Day 14: Clear CTA

• First email in sequence has highest open rate — make it count
• Space emails 1-3 days apart — daily is too aggressive for most audiences

Segmentation

• Segment by behavior, not just demographics — what they clicked matters more than job title
• Minimum viable segments: new subscribers, engaged (opened in 30 days), unengaged, customers
• Tag on every click — builds behavioral profile automatically
• Sunset unengaged subscribers after 90 days — send re-engagement, then remove
• VIP segment for highest engagement — reward them with early access, exclusives

Timing and Frequency

• Tuesday-Thursday mid-morning performs best on average — but test your audience
• B2B: business hours. B2C: evenings and weekends can work
• Frequency depends on value: daily works if valuable, weekly fails if boring
• Let subscribers choose frequency — reduces unsubscribes significantly
• Send time optimization: most ESPs offer this, use it

Campaign Types

• Newsletter: regular value, builds relationship, low direct conversion
• Promotional: clear offer, urgency, direct conversion focus
• Transactional: receipts, confirmations — highest open rates, add value here
• Re-engagement: "We miss you" + incentive + easy unsubscribe
• Announcement: product launches, major updates — segment to interested only

Writing for Email

• One goal per email — multiple CTAs dilute response
• Write for skimmers: bold key phrases, short paragraphs, bullet points
• P.S. lines get read — put secondary CTA or key point there
• Plain text often outperforms HTML for personal-style emails
• Mobile-first: 60%+ open on mobile — single column, large tap targets

Automation Triggers

• Sign up → Welcome sequence
• Purchase → Onboarding + cross-sell sequence
• Abandoned cart → 3-email recovery (1h, 24h, 72h)
• No open in 30 days → Re-engagement sequence
• Link click → Tag and trigger relevant follow-up
• Date-based → Birthday, renewal reminder, anniversary

A/B Testing

• Test one variable at a time: subject, send time, CTA, from name
• Need 1000+ recipients per variant for statistical significance
• Subject line tests: 20% of list first, winner to remaining 80%
• Measure what matters: opens for subject, clicks for content, conversions for offers
• Document every test — institutional learning prevents repeat experiments

Common Mistakes

• Sending to entire list always — segment or face declining engagement
• No double opt-in — leads to fake emails and spam traps
• Ignoring mobile preview — broken layouts kill credibility
• Same email to all segments — personalization is expected now
• Hard selling too early — value first, offer later
• Ignoring unsubscribe feedback — they tell you what's wrong

Compliance

• Include physical address in every email — required by CAN-SPAM, GDPR
• Unsubscribe must work within 10 days — one-click preferred
• Honor opt-outs immediately — delayed removal is illegal in many jurisdictions
• GDPR: explicit consent required, document it, allow data deletion
• Separate consent for different email types — marketing vs transactional