Email Marketing · · 1 min read
Gmail’s AI Inbox and the End of the Open Rate: How to Measure Email in 2026
Gmail's Gemini features now summarise and sort email by relevance, and open rates have been unreliable for years. Here's how to measure email marketing in 2026, and how to stay visible in an AI-sorted inbox.
In short:
- Gmail increasingly uses Gemini to summarise emails and rank messages by relevance, including within the Promotions tab.
- Open rates have been unreliable since Apple Mail began pre-loading tracking pixels. AI summaries make them even less meaningful.
- Measure email by clicks, revenue per recipient, conversions and list health.
Gmail has been adding Gemini-powered features steadily: AI summaries at the top of messages and an AI-organised inbox view that highlights what Google thinks matters most. Reports on how widely the AI Inbox has rolled out differ, but the direction is clear. Gmail is deciding more about what people see first, based on relevance and engagement.
Why open rates don’t tell you much anymore
- Apple Mail Privacy Protection pre-loads images, so many “opens” are machines, not people.
- When Gmail shows an AI summary, a person may get the message without opening it in the usual way.
- Subject line tests based on open rate can pick the wrong winner.
What to measure instead
| Metric | Why it matters |
|---|---|
| Click rate | Real interest in your content |
| Revenue per recipient | Compares campaigns of different sizes fairly |
| Flow revenue share | How much your automations earn without new effort |
| Spam complaint rate | Keep it well under 0.3% (Google’s limit) |
| Unsubscribe rate | Early warning that frequency or content is wrong |
How to stay visible in an AI-sorted inbox
- Get engagement, not just sends. Gmail’s ranking leans on how people interact with your emails. Send less to people who never engage.
- Make the first lines count. AI summaries pull from your content. Put the key message and offer clearly near the top.
- Use real text, not one big image. AI can’t summarise an image well.
- Keep authentication strong (SPF, DKIM, DMARC) and complaints low.
PeachTag Team
Led by Zain Ismail, 11+ years in performance marketing. Need help with this? Talk to us.
