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
| Metric | Healthy | Warning | Critical |
|---|---|---|---|
| Open rate | >20% | 10-20% | <10% |
| Click rate | >2% | 1-2% | <1% |
| Bounce rate | <2% | 2-5% | >5% |
| Unsubscribe | <0.5% | 0.5-1% | >1% |
| Spam complaints | <0.1% | 0.1-0.3% | >0.3% |
- 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