AI summaries are no longer a background feature. They now shape what recipients see in their inboxes and what they act on next. Our goal is simple: to show you where you can guide AI summaries in Gmail and Apple Mail and where control stops.
Key takeaways
- Inbox previews now affect opens before a message is read.
- Apple Mail and Gmail surface value in different ways.
- Visual previews and deal elements can replace the preheader.
- Structure and clarity guide what AI highlights.
- Some emails cannot be adjusted, which is expected.
The fight for conversion starts before the email is opened
For many campaigns, the first decision is made with the Promotions tab or inbox list, not inside the email. This decision is shaped by AI summaries and enriched previews, which sit between the sender and the recipient.
On Apple devices, Mail can show an AI-generated summary directly under the subject line on the inbox list. This line is not the preheader and is not pulled from a specific HTML field. It is written by the client based on what it reads in the message. Apple designed it as a user setting to enable recipients to switch summaries on or off. Apple notes that these summaries can vary and should be reviewed for accuracy. The result is a preview that can change according to the device used and the user’s preference.
Gmail follows a different path. With the Promotions tab on its mobile version, Gmail can surface visual cards and deal with details alongside the subject line. These elements allow recipients to interact with a promotion without opening the email at all. As a result, the preview becomes a mix of subject line, image, and offer data. When that happens, the preheader often drops out of view.
At the same time, Gmail generates AI summaries after the email is opened. These summaries appear directly above the email content, between the inbox view and the message itself. They do not affect the open decision, but they shape how recipients read and interpret the email once they open it.
This is why conversion work now starts earlier. If the preview is weak, unclear, or off-topic, the email may never be opened, even when the offer is solid. Writing and design choices at the top of the message set the tone for what AI extracts and shows first.
Why inbox optimization now matters more than ever
If you want a steady performance, you need to write for the inbox view first. For most teams, this means prioritizing the two clients that shape the bulk of real-world opens and previews.
Gmail and Apple Mail account for most email opens.
Almost 90% of email opens have been reported as from Apple Mail and Gmail.
This dominance is evident in reports for a few practical reasons:
- Apple Mail is widely used on iPhone and Mac, and its privacy protection affects how opens are recorded across many sends;
- Gmail has massive consumer and business usages, and its tabbed inbox means a large share of marketing newsletters land in the Promotions tabs;
- many other clients exist, but they account for a smaller proportion of tracked opens in most dashboards.
If almost 90% of opens show up as Apple Mail or Gmail, optimizing previews for these two environments is not optional. A small change in how these inboxes summarize or package your email can move your results to more than weeks of fine-tuning copy inside the message.
Inbox mediation is the new reality.
Email clients are no longer neutral containers. They decide what to surface, what to compress, and what to place front and center in the preview.
Email clients no longer just display emails; they interpret them.
In Gmail Promotions, annotations are built to make emails “come to life” with images, deals, and expiration dates, driving interactions from the Promotions tab itself.
In Apple Mail, the inbox can show AI-generated summary previews automatically under each email, not the preheader. Recipients can also turn summaries off and fall back to the first line instead.
The inbox is now an interpretation layer. Gmail decides whether to show a promo card, deal badge, or image preview. Apple decides whether the preview line is your first sentence or its own summary.
Gmail and Apple Mail interpret the same email differently
The same newsletter can look like two different messages depending on where it lands. Apple Mail can replace the preview line with an AI-written summary, whereas Gmail can swap the usual preview into a Promotions card with images and deal details. This difference changes what recipients notice first.
How Apple Mail builds inbox previews and summaries
Apple Mail can automatically show a summary preview under each email in the inbox when Apple Intelligence is enabled.
A few practical limits matter here:
- availability depends on the device model, language, and region, so AI previews are not universal across the inbox list;
- recipients can turn “Summarize Message Previews” on or off, which changes what they see in the inbox list.
Apple’s preview line can be an AI summary. Subscribers cannot rely on the preheader strategy in the same way because they may see an Apple-generated line instead.
How Gmail builds previews, summaries, and annotations
Gmail’s Promotions experience is built around preview enrichment. Promotions annotations support images, deals, and expiration dates through markup (Google Developers and Promotions annotations overview).
Two details matter for marketers:
- annotations use JSON-LD in the email header, with types such as PromotionCard and DiscountOffer (deal annotations; Google Developers and Promotions annotations reference);
- visibility is not guaranteed; Gmail warns that annotations might not be shown to all recipients because of quality filters and frequency limits (Google Developers and Promotions annotations overview).
Gmail’s preview enrichment is structured: If you give it explicit fields such as image URL, headline, discount details, and expiry, you increase the chance of Gmail surfacing them. It is still not guaranteed.
Side effect: AI summaries break storytelling emails
Story-first newsletters can suffer in inbox previews.
On Apple Mail, the inbox preview can be either an AI summary or the first line of the email, depending on the recipient’s settings. This makes narrative openings fragile in the inbox list.
On Gmail, Promotions can show image previews and promo elements that pull attention away from your teaser copy and toward whatever Gmail chooses to surface in the tab UI.
If your story starts slow, the inbox experience might collapse it: Apple Mail may summarize it into something plain or show your first generic sentence, whereas Gmail may surface a visual card and reduce the role your preheader used to play.
When previews stop being text: Gmail banners and promo annotations
In the Promotions tab, Gmail can replace the familiar text preview with visual elements. At that point, the inbox view stops behaving like a list of messages and starts acting like a feed of cards.
What happens when Gmail shows a banner
Gmail Promotions annotations support single-image previews, product carousels, and deal annotations with price and expiration details. Recipients can interact with these elements directly from the Promotions tab, without opening the email.
In Promotions, the preview can become a subject line plus an image preview card. This shifts the open decision from copy-first to visual-first. The image, not the preheader, carries most of the weight.
What marketers don’t control
Gmail states that multiple factors affect whether annotations appear. These include quality filters and frequency limits. As a result, visibility is not guaranteed, even when markup is correct.
You can submit a perfect annotation and still not have it shown to every subscriber. Gmail reserves the right to suppress or limit it.
With that said, it is still worth trying.
Even when annotations are not displayed due to markup, Gmail may still generate previews on its own. For example, when product images follow the same size and layout rules, Gmail can automatically group them into visual cards. In practice, that means structure and consistency can still work in your favor, even without full annotation support.
Why is this risky
Preview elements are conditional and can override the role of teaser preheader copies. A weak or contextless visual can cost the open, even when the offer itself is solid. If the selected image does not explain the value on its own, the preview gives the recipient little reason to continue.
At the same time, skipping optimization does not remove the risk. If you do nothing, Gmail will still decide how to preview your email at its own discretion. In many cases, that result is less predictable than a preview you have tried to guide yourself. Trying gives you a chance. Not trying to hand over the decision over entirely.
How marketers can influence AI summaries and inbox previews
Full control is not realistic, but guidance is. Gmail and Apple Mail both respond to clear structures, explicit signals, and early value cues.
Influence both Gmail and Apple Mail through content structure
Apple Mail summaries can replace first-line preview behavior, and recipients can toggle summaries on or off. That makes the opening lines important in both cases: Clear first sentences matter when summaries are off, and clear extractable meaning matters when summaries are on.
Gmail can surface structured promo elements when it reads a clear offer and layout. A clean structure increases the chance of the right elements appearing in the preview.
Practical writing and layout rules help across both clients:
- put the offer early, in text;
- use scannable structure so both humans and clients extract the same meaning;
- do not hide the value in a single image; give the client something textual to work with.
These steps do not guarantee how previews look, but they reduce randomness and improve the odds that the inbox view reflects the message you want recipients to see.
Influence Gmail through promo annotations and schema
Gmail Promotions annotations enrich previews and allow recipients to engage from the Promotions tab without opening the email.
Markup uses JSON-LD in the email header and supports specific types:
- PromotionCard for image previews;
- DiscountOffer for deal badges;
- fields such as discountCode, description, promo URL, and expiration date.
There are also constraints to keep in mind:
- supported image formats and aspect ratios;
- uniqueness rules for carousel images;
- frequency limits that can reduce how often previews appear.
Use Promotions markup to provide Gmail with explicit preview components: sender logo, image previews, headline, price, discount value, promo URL, and expiration. Treat it like SEO for the inbox: Structured fields beat implied meaning. Still expect throttling, as Gmail can suppress annotations through quality filters and frequency limits.
Why inbox visuals don’t live forever
Visual previews in Gmail are not permanent. Google explicitly calls out frequency limits for Promotions annotations visibility. Even when markup is correct, Gmail can reduce how often image cards, carousels, or deal badges appear.
Even when you do everything right, Gmail can cap how often these visual elements show up. Treat inbox visuals as something to monitor and refresh, not as a one-time setup. Rotating images, updating offers, and reviewing preview performance over time help keep Promotions previews relevant instead of stale.
Where control ends: emails you can’t optimize
Some limits sit outside the marketer's control, and it helps to plan for them early.
Gmail Promotions annotations are built for the Promotions tab. They do not apply to system-generated transactional layouts, and even for promotional emails, visibility depends on filters and frequency limits.
For receipts and system confirmations, the layout is often fixed by the sender system, and the optimization surface is smaller. Even for promotional emails, Gmail and Apple Mail retain user and platform controls. Planning with these boundaries in mind avoids chasing results that you cannot influence.
Wrapping up
Inbox previews now decide more than subject lines alone. Apple Mail and Gmail interpret emails before recipients read them, and that interpretation shapes opens and engagement. You cannot control every outcome, but clear structure, explicit offers, and thoughtful use of annotations guide what these clients show first.
Design emails for interpretation, not just for reading, and review inbox behavior as part of regular campaign checks.
0 comments