Why this matters
Each intervention is discrete and dated, which makes each one a natural experiment a sender can measure a before-and-after against (see measuring intermediation). Most of these changes add a layer of filtering, ranking, or summarisation between the sender and the recipient, and most are framed by the platform as a user-protection feature. The practical upshot for a programme is that the inbox and the lock screen are moving targets, and the levers that survive are authentication, list hygiene, and engagement.
Email and push interventions
| Date | Intervention | Note |
|---|---|---|
| Sep 2021 | Apple Mail Privacy Protection (iOS 15) | Image proxy inflates opens 30 to 50% on Apple heavy lists; the Mozilla/5.0 user agent becomes the canonical proxy signature. |
| Sep 2021 | iOS 15 Focus and interruption levels | Four level taxonomy; time sensitive is the only addressable level and is not for marketing. |
| Aug 2022 | Android 13 runtime notification permission | Opt in becomes an explicit grant; opt in rates fall sharply. |
| Feb 2024 | Gmail and Yahoo bulk sender requirements | SPF, DKIM, DMARC alignment, RFC 8058 one click unsubscribe, spam rate under 0.3%. Microsoft followed May 2025; Google escalated to rejection Nov 2025. |
| Oct 2024 | iOS 18.1 Apple Intelligence notification summaries | On iPhone 15 Pro forward; the sparkle icon appears. |
| Jan 2025 | iOS 18.3 disables news and entertainment summaries | After the BBC complaint; the cleanest natural experiment for the summarisation effect. |
| Nov 2025 | Pixel notification summaries and Organizer | Pixel 9 and 10; the December follow up auto categorises and silences low priority alerts. |
| Jan 2026 | Gmail AI Overviews and AI Inbox | Powered by Gemini 3; email summarisation default on mobile in most regions. The most aggressive email intermediation since the Promotions tab. |
| early 2026 | Galaxy S26 One UI 8.5 Notification Highlights | On device summarisation on Samsung’s stack. |
| Feb 2026 | Microsoft pulls Copilot Priority View from Outlook mobile | Cost and feedback driven; Prioritize My Inbox itself continues across clients. |
Sender cooperative signals
The signals senders get back are aggregate and deliverability-focused: Gmail Postmaster Tools (aggregate spam rate and reputation by IP and domain) and Microsoft SNDS. The one proposal toward more is draft-brotman-aggregate-performance-reporting, an IETF draft (March 2026) proposing daily aggregate JSON classification and engagement reports keyed by DKIM domain. It is aggregate rather than per-message, email-only, has no summarisation hook, is voluntary for the provider, and sits at an early IETF state.
The earlier intermediation layer
The summarisation panic is a thin layer on a much older story: Gmail tabs since 2013, Outlook Focused Inbox since 2016, machine learning spam filtering since the late 1990s, Android notification channels since 2017, and Focus modes since 2021. A user who silenced your channel in 2019 has been a non engager for years that nobody measured.
Related
Citations
[1] Apple, protect email privacy in Mail (Mail Privacy Protection hides IP and preloads images) [2] Google, email sender guidelines (bulk sender requirements) [3] Google, the 2013 tabbed inbox (Promotions and other tabs) [4] 9to5Mac, iOS 18.1 ships Apple Intelligence notification summaries [5] TechCrunch, Apple pauses AI notification summaries for news after false alerts [6] RFC 8058, one-click unsubscribe [7] IETF, draft-brotman-aggregate-performance-reporting