AI Inbox-Proof in 3 Steps: Readability, Relevance, and Frequency

AI is playing an increasingly important role in the inbox. It determines—using agents or algorithms—whether your email reaches the recipient. Here, we explain exactly what’s changing and what the impact of these changes is.

In this blog post, we’ll explain how you can ensure that your emails and your brand remain visible in the AI-driven inbox. In other words: how do you make your email (strategy) AI-inbox-proof? We’ll cover three topics:

1. Readability takes priority over design.

We often try to entice consumers with attractive visuals. But today’s text-based AI models prefer text over images. That doesn’t mean design isn’t important. It does mean, however, that text takes the lead—both in terms of content and from a technical standpoint:

Readable content

Make the readability of your emails a priority. Images serve as visual aids and help emphasize your message.

Single-minded messaging works better for customers, but certainly for AI as well. So make sure your email conveys a single message, with one main call to action. Carry this message throughout the entire email to create a single, consistent, and recognizable narrative. Ensure consistency between the subject line, pre-header, and introduction. That way, both the AI and your recipient will know why this email was sent and what action they should take.

Once your main message has been conveyed and deemed relevant by AI, your images become important. They provide the context and visual appeal for the ultimate reader: your consumer.

Technically readable emails

Your emails must also be easy to read from a technical standpoint. Make sure the images in the text aren't too large—both in terms of file size and in relation to the text.

Keep the file size of each image under 330 kB. The total size of the email should not exceed 1 mB. For the text-to-image ratio, we recommend a 65-35 ratio: 65% text to 35% images. If necessary, you can adjust this to a 60-40 ratio. On the one hand, this ensures that your email isn’t flagged as spam by email clients due to an excess of images. On the other hand, it ensures you still include enough images to visually complement the text for your customers.

Use HTML text in your emails. Be sure not to hide text within images. Text in images is less reliable for AI. Additionally, images don’t always load. This applies to titles and the introduction, as well as the text in the call-to-action button.

Also, make sure your emails comply with SPF, DKIM, and DMARC security requirements. These verify your authenticity as the sender. If you don’t comply with these requirements, email clients will flag your emails as spam. That significantly reduces the chances that your customers will even read them.

Have you finally reached your target audience?

Also, make sure the site is easy to read on mobile devices. Use a responsive design. Optimize your CTA buttons, font size, and line spacing for mobile.

It would be a shame to end up losing customers because of mobile design.

So what now?

So you have a lot of control when it comes to sending readable emails. The great thing is that if you make sure AI can read your emails, they’ll also become much more appealing to consumers. Have you made all your emails readable yet? Great—then you’re ready for step 2: relevance.

2. Relevance must be explicit

AI must be able to understand why your email is relevant to the recipient. Relevance is the key to being placed in the priority inbox, to being accurately summarized by AI, and to being noticed by an AI agent.

Consumer behavior plays an important role here. By responding to it, you create explicitly relevant touchpoints. The consumer is therefore the driving force: when he or she takes action, you take action as well—you entice your consumer to take the next step, leading to a (subsequent) purchase.

What can AI see, and what can't it see?

An AI agent with access to multiple data sources can also detect behavior outside the inbox, such as a product viewed or a purchase made. Without that connection, AI can’t read between the lines. Therefore, always explicitly state why your email is relevant at that moment (for example: “You left a product in your shopping cart”).

From one-to-many to one-to-one

Do you still mainly send one-to-many emails? If so, focus on these 6 behavior-driven journeys, ideally supported by a CDP:

1. Post-purchase

Manage all communication related to a purchase yourself (delivery, registration, reviews, cross-selling) so that you remain in control and maintain consistency.

2. Abandoned Cart

Classic and effective; expand it with a reminder for those who didn't open the email.

3. Abandoned category

When a user views a product category multiple times: acknowledge their interest and show relevant products or reviews.

4. Abandoned Browse

For brief, casual website visits: encourage visitors to keep browsing or provide inspiration.

5. Back in stock

Notify users when a favorite product is in stock; highly relevant, especially for opt-in users.

The customer journey must be right

Will you choose a journey from the abandonment series, or perhaps the post-purchase or back-in-stock series? They all have one thing in common: explicitly relevant emails direct your customers to a relevant landing page. Once you’ve enticed your customers to revisit your website with a follow-up that’s tailored to their behavior, don’t let them land on a generic page.

Make sure this customer journey is seamless from start to finish.

So what now?

Have you decided how you’re going to make your emails relevant? If so, make sure to structure your email schedule now to strike a balance between customer journeys and newsletters. How? You’ll find out in the third section: Frequency.

3. Frequency Follows Relevance

Your emails are clear and relevant. The final piece of the puzzle for an AI-inbox-proof strategy is finding the right frequency: how often do you send emails, and to whom?

The goal isn't to send fewer emails, but rather to establish a logical rhythm. Stick to your sending schedule, but gradually fill it with behavior-driven emails instead of generic newsletters. Relevant, triggered emails always take priority over the newsletter.

No interaction?

Adjust the frequency. Use data to determine where the threshold lies:

What is the average purchase frequency?
How much time elapses between website visits?
When does a lack of response become a sign of disinterest?

Based on this, place inactive customers in a separate segment and reduce the email frequency for that segment in line with their level of engagement.

Even inactive customers deserve to be treated as relevant. These journeys work for all customers, even those without recent activity. A CDP integration adds an extra layer of personalization:

1. Birthday Email

Keep it up to date (for example, with popular gifts) and test the best timing: on the day itself, a day earlier, or with an advance notice and a reminder.

2. Relationship Anniversary

Celebrate your first purchase or sign-up—a special moment of your own amid all the birthday emails.

3. New for You

Link new collections, features, or content to previous interests and explain why this is relevant. Is that too much trouble? If so, consider whether the email is really necessary.

4. Next Best Offer

Include the most logical follow-up offer based on purchasing and browsing behavior; this can also be effectively used as an additional layer in existing newsletters.

What about the newsletter?

The newsletter remains important for the relationship, but it is always secondary to behavior-driven journeys. Apply the readability tips here as well, and where possible, use personalized offers via a CDP. Tailor the frequency to your customer’s engagement: too little contact and you’ll be forgotten; too many irrelevant emails increase the risk of spam complaints, irritation, and unsubscribes.

Ready to get started?

Now you’re ready for the AI inbox: Your emails are easy to read, relevant, and have a rhythm tailored to your interactions with your customers. Great job! Would you prefer personalized advice? We’d be happy to help you figure it out.

Please contact Roos. She’d be happy to help you figure things out. Or use our contact form.