AI now sits between your email and your customer. Gmail summarizes threads with Gemini and is testing an AI Inbox that surfaces priority mail, while Apple Mail shows AI-written summaries in place of your preview text. To adapt, put the key message and offer in the first two sentences, structure emails clearly, and measure clicks and revenue rather than opens.
- On January 8, 2026, Google began rolling out Gemini features in Gmail, which 3 billion people use: free AI thread summaries and writing help (U.S. and English first), with an AI Inbox in testing.
- Apple Intelligence can show an AI-generated summary in the inbox in place of the preheader you wrote.
- Since September 2025, Gmail's Promotions tab can sort by relevance instead of recency, so engagement matters more than send time.
- Email is still a core channel: about 75% of marketers plan to maintain or increase email investment in 2026 (HubSpot).
How is AI changing the email inbox?
Your subscribers now often meet a summary of your email before (or instead of) the email itself. Three changes matter most:
- Gmail's Gemini era. On January 8, 2026, Google announced AI features for Gmail, starting in the U.S. in English. Thread summaries (AI Overviews), Help Me Write and Suggested Replies are free for all users; asking your inbox questions and Proofread are part of paid Google AI plans. An AI Inbox that filters low-priority mail and surfaces what matters is in testing with a broader rollout planned.
- Apple Mail summaries. Apple Intelligence can generate pre-open summaries that appear in the inbox list and replace the preheader text you wrote.
- Relevance-sorted Promotions. Gmail's Promotions tab can sort by relevance rather than date, so brands people don't engage with sink.
What your subscriber may see now (illustration)
AI-generated summaries increasingly frame your message before the email does
Riverbend Dental is offering fall cleaning appointments through October 31. New patients get a free whitening consultation. Book online or call.
Simplified illustration. Businesses shown are fictional. Summary placement differs between Gmail (after opening) and Apple Mail (in the inbox list).
Do AI summaries hurt email open rates?
They change what an "open" means. Gmail's Gemini summaries appear after someone opens an email, so they don't directly change open rates. Apple's pre-open summaries are different: they take over the preview space next to your subject line, so a vague first sentence can become a vague summary.
Open rates were already unreliable. Apple's Mail Privacy Protection automatically "opens" messages to preload images, and one 2026 industry estimate (Geysera, via Plotline) put machine opens at nearly half of tracked opens. Treat opens as a rough health signal, not a success metric.
3B
people use Gmail, where Gemini summaries are rolling out (U.S., English first)
Google, Jan 2026
~75%
of marketers plan to maintain or increase email investment in 2026
HubSpot, 2026
8.4%
of marketers name open and click rates as their most important email metrics
HubSpot, 2026
How do you write emails that AI summarizes well?
Write the summary yourself, at the top. AI summarizers pull from the beginning and from the clearest structure in the email. Make both work for you:
Anatomy of an AI-summary-friendly email
What a summarizer is most likely to pick up, top to bottom
Specific subject. Clear topic plus a reason to act now.
Summary sentence. The first 100–200 characters carry the whole message.
Live text, not an image. AI (and screen readers) can read it.
• Most insurance accepted
• 2 minutes to book online
Scannable proof. Short bullets summarize cleanly.
One explicit CTA. A specific action survives summarization.
- Front-load the value. Your first one or two sentences should say who it's for, what's new and what to do, in about 100–200 characters.
- Use real text, not one big image. AI can't summarize a graphic. Lead with live text and use images to support it.
- Structure with headings and short bullets. Clear structure produces clear summaries.
- Make the call to action explicit. "Book your free consultation by Friday" survives summarization; "Learn more" doesn't.
- Keep one message per email. Three offers produce a muddy summary.
What should you measure instead of opens?
Measure what happens after the email. Clicks, replies, bookings, purchases and revenue per email are the numbers that tell you whether email is working. Engagement also feeds Gmail's relevance sorting, so a smaller list of engaged subscribers often beats a large, cold one.
This is also why automated emails (welcome series, post-purchase follow-ups, appointment reminders, win-backs) deserve attention. They're triggered by customer actions, so they're timely and relevant by design. Exactly what AI-sorted inboxes reward.
Your AI-inbox email checklist
- Rewrite your first two sentences so they work as a standalone summary.
- Replace image-only headers with live text plus supporting images.
- Use one primary call to action with a specific verb and deadline.
- Clean your list: sunset subscribers who haven't clicked in 6–12 months.
- Report on clicks, conversions and revenue, not opens alone.
- Set up 2–3 automated flows: welcome, post-purchase or post-visit, and win-back.
Frequently asked questions
Does Gmail summarize marketing emails with AI?
Yes. Since Google's January 2026 Gmail update, Gemini can generate AI summaries (AI Overviews) of email threads, and that feature is free for all users. Summaries appear after an email is opened. Google is also testing an AI Inbox that filters low-priority mail.
Do Apple Mail AI summaries replace my preheader?
They can. Apple Intelligence can show an AI-generated summary in the inbox list in place of the preview text, and senders can't turn this off. That's why the first sentences of your email body matter as much as the preheader.
Are email open rates still reliable?
Not very. Apple Mail Privacy Protection preloads emails and registers opens automatically, and AI features add more noise. Use opens as a rough deliverability signal and judge performance by clicks, replies, conversions and revenue.
Is email marketing still worth it in 2026?
Yes. About 75% of marketers in HubSpot's 2026 State of Marketing report plan to maintain or increase email investment. Email remains a direct, owned channel, and well-targeted automated emails are especially effective in AI-sorted inboxes.
Turn this into real momentum.
Book a free growth audit. We'll look at what's working, what's getting in the way, and where your strongest opportunity is. Learn more about our Email Marketing services.
Get your free growth audit ↗Keep reading
- Google Now Says Fact-Check Your AI Content. Here's a Human-in-the-Loop Workflow That Works
- ChatGPT Ads Are Here: Should Your Small Business Advertise on ChatGPT?