Deliverability is the most important conversation in email marketing that almost no one wants to have. It is not glamorous. It does not produce dashboards full of impressive looking numbers. But it sits underneath everything else. If your emails are not actually reaching the inbox, none of your strategy, copy, design, or segmentation work matters. You are simply sending into the void and paying for the privilege.
The reason deliverability has become such a hot topic in 2026 is that the rules quietly changed in early 2024, and the changes have steadily tightened ever since. Google and Yahoo introduced strict new requirements for bulk senders. Apple Intelligence and inbox summary features altered how emails are perceived once they do arrive. Klaviyo and every other major email platform have had to adapt, and so have the brands sending through them.
If you are running Klaviyo and you have not thought carefully about deliverability in the last 12 months, this is the post that will explain what changed, what it means for your store, and what to do about it.
The Google And Yahoo Bulk Sender Rules
In February 2024, Google and Yahoo introduced new rules for any sender pushing more than 5,000 emails per day to their respective platforms. The rules have since become the de facto standard across the email industry, regardless of whether you cross that threshold. Other major mailbox providers have aligned their policies in the same direction.
There are three core requirements you need to meet.
First, your sending domain must be properly authenticated with SPF, DKIM, and DMARC. These are technical standards that let receiving servers verify that an email actually came from where it claims to have come from. Without them, your emails are increasingly likely to be filtered into spam or rejected outright. Klaviyo provides guidance on setting these up, but the configuration has to happen in your domain provider, and many founders never complete the process correctly.
Second, you must keep your spam complaint rate below 0.3 percent, ideally below 0.1 percent. A spam complaint is what happens when a recipient marks your email as spam in their inbox. Even one mass complaint event can damage your sender reputation for weeks. Brands that send too aggressively, send to disengaged subscribers, or use deceptive subject lines tend to hit this ceiling far faster than they expect.
Third, you must offer one click unsubscribe headers in your emails, in addition to the visible unsubscribe link in the footer. Klaviyo handles this for you automatically as long as your account is configured correctly, but it is worth double checking that the feature is enabled on your account.
Compliance with these rules is no longer optional. Senders who do not meet them see their emails routed to spam folders or blocked entirely. Senders who do meet them have a much stronger foundation for landing in the primary inbox.
How Apple Intelligence Changed Inbox Behavior
Apple Intelligence, which rolled out broadly across iOS and macOS in 2024 and 2025, introduced features that affect how emails are read and perceived on Apple devices. Two changes matter most for marketers.
The first is automatic email summaries. Apple Intelligence now generates short summaries of incoming emails and displays them in the inbox preview. This means the subject line is no longer the only thing competing for attention. The summary, generated automatically from the email’s content, often appears alongside or even instead of the preview text you carefully wrote.
The implication is that your email content has to be clear and well structured from the very first line. The opening of your email is no longer just for the reader. It is also for the AI summary engine that will paraphrase what you wrote. Hidden preview text, clever opening jokes that rely on the next line for context, and dense paragraphs of formatting all tend to summarize badly.
The second change is smarter inbox triage. Apple Mail now uses on device intelligence to sort incoming email into priority and less important groups, based on signals like sender reputation, past engagement, and content patterns. Emails that get sorted into the lower priority tier are still delivered, but they are less likely to be opened in the moment they arrive. This makes consistent engagement from real recipients more valuable than ever, because recent engagement is one of the strongest signals these systems use.
What Klaviyo Does To Help You Stay Deliverable
Klaviyo has invested heavily in deliverability tools over the past few years, and most of them sit quietly inside your account waiting to be used.
The platform offers a deliverability dashboard that shows you key signals like sender reputation, complaint rate, bounce rate, and engagement rates over time. Most founders never open this dashboard. Looking at it monthly is a small habit that catches problems early, before they become emergencies.
Klaviyo also provides a smart sending feature that automatically suppresses sends to subscribers who have already received a message recently. This protects against accidental over sending and helps maintain engagement rates by not exhausting your most active subscribers.
The platform’s segmentation tools can be used proactively to protect deliverability. Sending only to engaged subscribers for routine campaigns, and reserving full list sends for your most important moments, keeps your engagement rates high and your complaint rates low. This is one of the most effective deliverability strategies in the entire toolkit, and it is built right into the platform.
Klaviyo also offers a sender domain warming process for new accounts. If you are setting up Klaviyo for the first time, or moving from another platform, your domain has no reputation yet. Sending in high volumes from a cold domain is one of the fastest ways to land in spam. A proper warm up, starting with smaller volumes to your most engaged subscribers and gradually scaling up, builds a healthy reputation that lasts.
Warning Signs You Are Landing In Promotions Or Spam
Most brands do not realize their deliverability has slipped until the damage has been done. There are a few early signals worth watching for.
Falling open rates over time, especially among segments that used to engage well, often signal that your messages are being filtered out of the primary inbox. Apple inflation has made this harder to read, but a consistent downward trend across multiple flows and campaigns is still a real signal.
Bounce rates creeping above 2 percent, or any sudden spike in bounces, usually mean your list contains low quality addresses or your sender reputation has slipped. Most healthy lists bounce at well under 1 percent.
Spam complaint rates climbing above 0.1 percent are an immediate red flag, even if you are still under the technical 0.3 percent ceiling. Complaints are the single most damaging signal you can generate, and the major mailbox providers act on them quickly.
A noticeable gap between your Klaviyo reported open rate and your actual engagement signals from other channels can also indicate filtering. If your dashboard shows healthy opens but your click rate, reply rate, and website traffic from email have all fallen, the opens you are seeing may be machine activity from filtered emails.
The Small Technical Fixes Most Stores Miss
Beyond the major rules, there are a handful of smaller fixes that quietly protect your deliverability and that many stores get wrong.
Sending from a subdomain dedicated to marketing email rather than your main domain isolates your reputation. If something ever goes wrong, your transactional emails from the main domain are protected.
Removing inactive subscribers regularly, ideally as part of an automated sunset policy, keeps your engagement metrics strong and your costs down. A subscriber who has not opened in 12 months is essentially dead weight, and continuing to email them costs you in deliverability, in money, and in time.
Avoiding spam trigger words and overly promotional formatting in your emails, especially in the subject line and opening lines, keeps you on the right side of content filters.
Keeping your image to text ratio reasonable. Emails that are essentially one big image with no text often get flagged by filters and also fail accessibility standards. A healthy email has real text, structured headings, and images that support the message rather than carrying it entirely.
Including a clear physical address in every email, as required by anti spam legislation in most countries, is another small thing that many stores still get wrong. Klaviyo prompts you to set this up, but it is worth confirming it is present and current.
Why Deliverability Is Worth Real Attention
If your emails are not reaching the inbox, every other email investment you make is wasted. Better copy does not matter. Better design does not matter. Better segmentation does not matter. The economics of email marketing depend on the foundation that your emails are actually being seen.
The good news is that strong deliverability is not difficult once it is set up correctly. It just requires attention, the right configuration, and a small set of ongoing habits.
At EHABY, deliverability is part of every flow build, every audit, and every monthly engagement we run. We configure sender domains correctly, monitor reputation actively, and build the segmentation and list hygiene practices that protect inbox placement long term. If your open rates have been sliding without explanation, or if you are not sure whether your Klaviyo account is even properly authenticated, book a free Klaviyo strategy call. We will run through your deliverability setup with you and identify exactly where the foundation needs work.