What’s happening?

• Gmail now surfaces subscription frequency and offers one-click unsubscribes, so over-mailing is visible and easy to correct from users’ side.
• Apple Mail / iOS add AI summaries, digest views and branded mail features, meaning clients may show automated previews instead of your preheader — design must serve both humans and automated summarizers.
• Industry best practice is shifting to engagement-first: segment by recent activity and measure meaningful engagement rather than raw opens.

12 tactical moves (actionable, prioritized)

1) Audit & fix authentication and reputation — must do

Confirm SPF, DKIM and DMARC are correctly set for sending domains; enable DMARC reports and register for Postmaster monitoring.

2) Add & verify List-Unsubscribe header + one-click unsubscribe

Ensure List-Unsubscribe: header (URL and/or mailto) and a one-click in-email unsubscribe. Map client unsubscribes back to your suppression lists.

3) Move to engagement-based sending & frequency caps

Segment by recency (e.g., prioritize 30-day active; limited sends to 90+ day). Cap frequency per segment (e.g., 1–3/wk active; 1/mo passive). Show frequency in preference center.

4) Build a real preference center — include “downgrade” options

Offer: Daily, 2–3×/week, Weekly Digest, Product-only, Order-only, Pause (30/60 days), Unsubscribe. Put the link in header/footer and re-engagement flows.

5) Design for AI and humans — put a clear TL;DR at the top

HTML + plain-text: first element should be TL;DR: — one line with offer + 1 benefit + CTA words. Make the top 1–3 lines (preview text) clearly state the offer.

6) Front-load text; make images optional

Don’t rely on images for the offer — use a strong textual headline, short bullets and a textual CTA at the top.

7) Use honest, predictable subject + preview pairing

Align subject → preview → top lines. Avoid clickbait and test how combos render in Gmail/Apple digest previews.