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

The ask	Route to
One-off product launch announcement or campaign drip nurture	`../marketing/SKILL.md`
Mail lands in spam; set up SPF / DKIM / DMARC, tracking domain, reputation	`../email-deliverability/SKILL.md`
Write the subscribe / opt-in landing page copy	`../landing-copy/SKILL.md`
Define the house voice, tone, and vocabulary the newsletter speaks in	`../brand-voice/SKILL.md`
Win back / reactivate lapsed paying customers (lifecycle, not readers)	`../retention/SKILL.md`
Produce the underlying long-form articles the issue links out to	`../content-engine/SKILL.md`
Sample size / significance / MDE math for the test itself	`../ab-testing/SKILL.md`
Source or scrape new contacts; prospect an un-opted-in list	`../lead-gen/SKILL.md`, `../cold-outreach/SKILL.md`
Actually wire the send through an ESP / Gmail API and schedule it	`../email-connector/SKILL.md`, `../google-workspace/SKILL.md`

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.