newsletter

Run the newsletter as a product you ship on a cadence, not a one-off send. The job is the system around the recurring issue: the subject + preview that earns the open, the issue body that earns the click, the welcome sequence that activates a new subscriber, the cadence and segmentation that keep the list healthy, the growth loops that compound it, and a scorecard that still tells the truth after Apple broke open rates. Every send is one episode of an ongoing show — design the show, not the episode.

When NOT to use — route instead

You own the recurring opted-in publication and its open/click/growth system. The plumbing under every send and the page that captures the signup are someone else's.

The metric truth after Apple MPP

Apple Mail Privacy Protection pre-fetches the tracking pixel, firing an "open" even when nobody read the email. It accounts for ~49% of all tracked opens and inflates reported open rate by ~15–35% on iOS-heavy lists — one beehiiv newsletter jumped from a 28% to a 55% open rate with zero behavior change. So stop steering on open rate. MPP does not touch link tracking, which is why the click is now the honest signal.

Rule: make click rate and non-Apple CTOR the north star, because the click is the one event MPP cannot fake. Leading 2025 programs removed open rate from decision-making entirely and anchor on clicks.

Calibration benchmarks (2025, cross-industry): average open rate ~42–43% (MPP-inflated, treat as noise), average click rate ~2.1% (range 0.83%–4.90%), click-to-open ~6.8%, conversion ~0.08% (top decile ~0.44%). Use the click figures to calibrate; ignore the open figure as a target.

The scorecard — track these, in this order:

Issue anatomy — one job per issue

Each issue gets exactly one job and exactly one primary CTA. A second CTA halves the first. Put the hook on the first screen (subject's promise paid off before any scroll), keep the body scannable (short paragraphs, one idea per block, links that read as links), and end at a single button-grade action.

Bad (rambling, no single job, CTA buried):
  Hey everyone! Lots going on this week — we shipped some updates, there's a
  webinar coming, I read a great book, and oh also our pricing changed, plus
  here are five links I liked. Anyway, check it all out when you get a chance!

Good (one promise, one payoff, one CTA):
  This week: the 3-line config change that cut our cold-start by 40%.
  • What it was   • Why the default is wrong   • The exact diff
  → Read the 4-minute breakdown   [single primary link]

Everything secondary becomes a one-line P.S. or a small "also" block, never a competing button.

Subject + preview as a pair

The subject and the preview (preheader) ship together and are tested together — they share the inbox row.

• Payload in the first ~33 characters; keep the whole subject ~30–50 chars (≈7–9 words) so it survives mobile truncation.
• The preview extends the subject, it never repeats it. Its first ~35–50 chars are prime real estate; waste them on a duplicate and you've burned the line.
• ≤2 emojis, at the end, never an all-emoji subject — an all-emoji subject is the one case that actually trips filters.
• The "spam trigger words" list is a myth. "Free", "guarantee", a normal emoji — these do not sink you; authentication and sender reputation dominate deliverability. Police reputation, not vocabulary; the reputation/auth layer lives in ../email-deliverability/SKILL.md.

Bad (payload past char 33, preview repeats subject):
  Subject:  We are very excited to finally share our big new feature today!!!
  Preview:  We are very excited to share our big new feature

Good (payload first, preview extends):
  Subject:  Cut cold-start 40% with 3 lines
  Preview:  The default config is wrong — here's the exact diff and why

Cadence & segmentation

Cadence is not one number for the whole list — it branches on how engaged the reader is. This is the decision table:

Sunset dormant addresses on purpose — complaint rate, not list size, gates the inbox. Mailing a decaying list harder is how a sender torches its reputation.

Send-time default: Tuesday/Thursday mid-morning (~10am) or early afternoon (1–3pm) is the cross-industry baseline — but treat it as a hypothesis to test against your own list's click data, not a law. Segmented sends earn roughly 100% higher click rates than blast-to-everyone, so segment before you optimize send time. Tier definitions and the full sunset/re-permission flow live in references/growth-loops.md.

The welcome sequence

A confirmed subscriber gets a 3–5 email sequence, not silence until the next issue — this window is the highest engagement they'll ever have. One job per email:

1. Deliver the promise (immediate) — the thing they signed up for, instantly. Sets the expectation that you ship value.
2. Set expectations + best-of (day 1–2) — what arrives, how often, plus your best past issue so they see the ceiling.
3. The referral ask (day 4–5) — once they've gotten value, ask them to share (the theSkimm pattern: referral ask inside the welcome, not bolted on later). 4–5. Optional: segmentation/preference capture and a feedback prompt.

Full skeleton with timing, subject+preview per email, and the one-job rule: references/welcome-sequence.md.

Growth loops

Three loops compound the list; depth and the dated numbers are in references/growth-loops.md.

• Referral — referral programs lift subscriber growth ~17% on average and can accelerate growth 20–200% (The Hustle's referral drives ~10%+ of its free-list growth). Put the ask inside the welcome sequence and at the issue footer, gated on tiered rewards.
• Signup incentive / lead magnet — a specific, immediately useful asset converts the subscribe far better than "join our newsletter". The asset is what gets shared.
• Double opt-in — confirm the address before it joins. It protects list quality and keeps the complaint rate down, which is what actually keeps you in the inbox. The subscribe page itself is ../landing-copy/SKILL.md.

Compliance baseline

A newsletter is the canonical bulk marketing message, so the Gmail/Yahoo bulk-sender rules (enforced since Nov 2025 for 5,000+/day senders) apply to every issue:

• RFC 8058 one-click unsubscribe (List-Unsubscribe + List-Unsubscribe-Post headers) on every send, plus a visible footer unsubscribe link. Both, always.
• Keep the spam-complaint rate under 0.1% and never let it reach 0.3%. This is why you sunset, not why you mail harder.

The DNS / authentication side of those rules — SPF, DKIM, DMARC, the sending domain — is not this skill; that is ../email-deliverability/SKILL.md. This skill applies the rules to the issue and the cadence.

A/B testing the right way

• Test exactly one element at a time — subject vs subject, or preview vs preview. Change two and the winner is uninterpretable.
• Put preview text in the rotation, not just the subject; it's half the inbox row and usually under-tested.
• The statistical design — sample size, significance, minimum detectable effect — is ../ab-testing/SKILL.md. This skill tells you what to test; that one tells you whether the result is real.

Anti-patterns

Verify

scripts/verify.sh is a read-only structural linter for a drafted issue file (subject: / preview: lines, body, footer). It checks subject length and payload position, that the preview exists and differs from the subject, emoji count, a single primary-CTA marker, and a present unsubscribe line. Run it on the draft before you ship — it never edits the file and exits 0 on an empty one.

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Supporting file: evals/cases.yaml

skill: newsletter

should_trigger:

• prompt: "Write the subject line and preview text for this week's newsletter issue." why: Core subject + preview pair job, fit to inbox truncation.
• prompt: "My newsletter has a 50% open rate but almost nobody clicks — what's wrong?" why: Non-obvious — high opens / no clicks is the post-MPP metric truth plus issue/CTA structure, the signature rescue case.
• prompt: "Set up a welcome sequence for new subscribers and work in a referral ask." why: Welcome/onboarding sequence plus the growth-loop referral ask placed inside it.
• prompt: "How often should I send my newsletter and how do I segment subscribers by engagement?" why: Cadence + engagement-segmentation decision table and the sunset policy.
• prompt: "What metrics should I trust now that Apple makes my open rate fake?" why: Non-obvious — the MPP metric-truth scorecard (clicks / non-Apple CTOR as north star).
• prompt: "Escriu la newsletter d'aquesta setmana perquè la gent l'obri i hi faci clic." why: Catalan — recurring-issue subject/body job (open then click).

should_not_trigger:

• prompt: "Write the launch announcement email for our new product drop." route_to: marketing why: One-off campaign send, not the recurring opted-in publication.
• prompt: "Our newsletter lands in spam — fix our SPF, DKIM and DMARC records." route_to: email-deliverability why: DNS / authentication / reputation plumbing, not the issue or cadence.
• prompt: "Write the subscribe landing page that captures newsletter signups." route_to: landing-copy why: The opt-in page copy, not the email or the list system.
• prompt: "Win back customers who haven't purchased in 90 days." route_to: retention why: Lifecycle/churn reactivation of paying customers, not newsletter readers.

capability:

• scenario: > A B2B SaaS founder is launching a weekly newsletter and asks for the first issue's subject + preview pair, a 3-email welcome sequence, and the success metric they should track. must_include:
  • "Subject line ≤ ~50 chars with the payload in the first ~33 chars, paired with a preview that EXTENDS rather than repeats the subject."
  • "The issue and each welcome email have exactly one primary CTA."
  • "A referral ask is placed inside the welcome sequence (not bolted on later)."
  • "The success metric is click-rate / CTOR-based (NOT raw open rate) with an explicit Apple MPP caveat."
  • "A visible unsubscribe line / one-click unsubscribe is noted as required on every send."
  • "DNS/auth (SPF/DKIM/DMARC) is deferred to email-deliverability rather than attempted here."

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Supporting file: evals/README.md

Evals — newsletter

These cases are read by the repo's skill-eval harness. should_trigger and should_not_trigger check routing precision: each prompt is matched against this skill's description versus its siblings (the route_to ids — marketing, email-deliverability, landing-copy, retention — must win their cases). The capability case is scored by a judge against its must_include rubric: it checks that a generated first issue actually produces a truncation-fit subject + extending preview, single-CTA emails, an in-sequence referral ask, a click/CTOR-based success metric with an MPP caveat, a present unsubscribe line, and that it defers DNS/auth to email-deliverability. Run them through the repo's eval runner; no live ESP, sending, or network access is required.

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Supporting file: references/growth-loops.md

Growth loops, segmentation, and the sunset policy

The list compounds through three loops and stays healthy through engagement tiering. Numbers below are dated; treat them as calibration, not promises.

Referral program

• Lift: referral programs raise subscriber growth ~17% on average and can accelerate growth 20–200%. The Hustle's referral drives ~10%+ of its free-list growth. (beehiiv growth guide; Partnero/Paved referral guides — accessed 2026-06-02.)
• Where the ask lives: inside the welcome sequence (email 3) AND as a persistent footer block on every issue. Asking once, late, wastes the loop.
• Reward tiers: make the first reward cheap and fast to unlock (e.g. 3 referrals) so subscribers get an early win, then ladder up. Digital rewards (archive access, a guide, swag) beat cash for newsletters.
• Mechanics: each subscriber gets a unique referral link; track referred signups, not raw shares. Reward only on confirmed (double opt-in) referrals so the loop does not import junk.

Signup incentive / lead magnet

• A specific, immediately useful asset converts a subscribe far better than a generic "join our newsletter."
• The asset doubles as shareable bait for the referral loop — make it good enough to forward.
• The opt-in page and its copy are ../../landing-copy/SKILL.md; this skill owns what the incentive is and how it ties into the welcome + referral flow.

Opt-in: single vs double

Default to double opt-in. Complaint rate and spam traps gate the whole sender's inbox placement; the confirmation click is cheap insurance. Segmented sends earn ~100% higher click rates than blasts, so a clean confirmed list also makes every later segmentation gain real. (Moosend segmentation 2025–2026 — accessed 2026-06-02.)

Engagement segmentation tiers

Heavy clickers can take more frequency; cooling readers get less, on a best-of track, before they sour.

Sunset / re-permission policy

Chronically unengaged addresses get a re-permission email ("still want this? click to stay") and, if no click, a sunset off the active list.

• Why: complaint rate, not list size, gates the inbox. A big dormant segment drags placement for everyone, including your heavy readers.
• Keep the spam-complaint rate under 0.1% (never reaching 0.3%) — sunsetting is the lever that protects it. (Yahoo Sender Hub best practices; Google Workspace sender guidelines — accessed 2026-06-02.)
• Re-permission is a newsletter-list hygiene step. Lifecycle reactivation of lapsed paying customers is a different job — that is ../../retention/SKILL.md.

Send-time hypothesis

Tuesday/Thursday ~10am or 1–3pm is the cross-industry baseline starting point. It is a hypothesis to test against your own list's click data, never a fixed law. The test design (sample size, significance) is ../../ab-testing/SKILL.md.

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Supporting file: references/welcome-sequence.md

Welcome sequence skeleton

The 3–5 emails a subscriber gets after they confirm. This window has the highest engagement they will ever show — every email earns one job and one CTA. Send the first one immediately on confirmation; space the rest over the first week.

The one-job rule

Each email answers a single question for the new subscriber. If an email is doing two jobs, split it or cut the weaker one. Never open the sequence with a sell.

Email 1 — deliver the promise (immediate, on confirmation)

• Job: hand over the exact thing they subscribed for, right now.
• Why first: the confirmation click is peak intent; a fast payoff sets the expectation that every issue ships value.
• CTA: consume the promised asset (read / download / watch) — one link.
• Subject + preview pair example:
  • Subject: Here's the field guide — start here
  • Preview: Plus the one section most people skip first

Email 2 — set expectations + best-of (day 1–2)

• Job: tell them what arrives, how often, from whom; then show your ceiling with one strong past issue.
• Why: predictable cadence lowers unsubscribes; the best-of proves the bar.
• CTA: read the best-of issue — one link.
• Subject + preview pair example:
  • Subject: What to expect (and our best issue)
  • Preview: Every Thursday, 4-minute read — here's the one to start with

Email 3 — the referral ask (day 4–5)

• Job: ask them to share, now that they have received value.
• Why: the theSkimm pattern — the referral ask lives inside the welcome sequence, not bolted on months later when engagement has decayed.
• CTA: share their referral link — one link.
• Subject + preview pair example:
  • Subject: Know one person who'd want this?
  • Preview: Your link's below — first reward unlocks at 3

Email 4 (optional) — segmentation / preferences (day 6–8)

• Job: let them pick topics or frequency so you can route them to the right engagement track from day one.
• CTA: set preferences — one link. Skippable; defaults must be sane.

Email 5 (optional) — feedback prompt (day 9–12)

• Job: ask one question ("what made you subscribe?") to mine future angles and surface at-risk subscribers early.
• CTA: reply to the email — replies also help inbox placement.

Rules across the sequence

• One primary CTA per email; secondary items go in a one-line P.S.
• Every email carries the visible unsubscribe footer (compliance is not optional in the welcome stream).
• Subject payload in the first ~33 chars; preview extends, never repeats.
• If they click in the sequence, they enter the active/heavy cadence tier (see growth-loops.md); if they never open the welcome stream, they go to the re-permission path before the main list.