The Perfect Storm: How Two Major Industry Changes Impacted Email Engagement

It often seems the one constant in the email industry is that the email industry is constantly changing! Mailbox provider requirements, email filtering, and technology (like Apple Intelligence) are rapidly evolving, leaving marketers to scrutinize the impact of these changes on their email programs.  

Earlier this year, we began to hear from a variety of senders that their email program performance was down year-over-year, so we decided to dig into our data to investigate further and provide an explanation for the decline in performance.  

What’s behind the drop in email engagement?

Here at Validity, our conversations with email marketers in early 2025 have all pointed to a persistent theme: a noticeable, and sometimes frustrating, dip in engagement. This feedback prompted us to dive into our own data, which confirmed the trend. However, the numbers alone don’t explain the full story. To understand what’s really going on, we need to explore the significant industry changes that are reshaping the inbox.

Let’s explore the combined impact of Apple Mail’s recent updates and Yahoo’s stricter sender enforcement to bring clarity to what marketers are experiencing. 

How iOS updates changed the inbox

Apple has been progressively rolling out improvements to the Mail app, starting with iOS 18.2 in December 2024 and expanding to iPadOS and macOS through March and April 2025. These updates introduced several new features that fundamentally alter how users interact with email. 

Key changes in Apple Mail 

• Inbox categories: Mail is now automatically sorted into “Primary,” “Transactions,” “Updates,” and “Promotions.” While designed to help users, this means marketing messages are often filtered out of a single lens by default. 

• AI-powered summaries: Instead of showing sender-defined preheader text, Apple Mail will now often display an AI-generated summary of an email’s content. This shifts the focus from a marketer-crafted “hook” to the core message itself. 

• Digest view and grouping: Messages from the same sender are now frequently stacked together. While this can declutter the inbox, it also means individual emails may not be seen unless a user actively explores the grouped digest. The risk of individual messages being overlooked is more significant for high frequency senders who are emailing segments with low engagement.  

The impact on engagement 

The initial adoption of these features is high because they are enabled by default. While users can customize their settings, many won’t. After all, these changes are, by design, intended to help Apple Mail users manage their email more efficiently.  

This creates a new challenge for marketers trying to understand how changes such as inbox categories impact subscriber experience. But it also presents an opportunity for senders to focus on email relevance and value, which can lead to more intentional opens from subscribers browsing these tabs. For those looking to adapt, we’ve explored why Apple Mail’s categorization can be a good thing. 

At Validity, our Everest platform includes an Engagement Pixel, giving users detailed analytics while providing insight into broader trends. This feature tracks the volume of pixel requests, which occur when an email is viewed or when Apple’s Mail Privacy Protection (MPP) pre-fetches images. This is where our own data helps shed some light on these trends. 

Looking at the year-over-year comparison below, we saw pixel request volume increase by about 7 percent in January and February of 2025. However, this trend reversed starting in March, followed by a significant 15 percent drop in April compared to 2024. By May, the numbers began to show signs of recovery. This timeline aligns perfectly with the rollout of Apple’s new features, establishing a clear link between the changes in the Mail app and the engagement shifts marketers have been reporting. 

Stricter sender enforcement at Yahoo 

While Apple was changing the user experience, Yahoo was tightening enforcement of bulk sender requirements. After announcing new requirements in 2024, Yahoo began strict enforcement in February 2025, with a more noticeable push in April. 

These changes were part of a broad industry movement towards stronger authentication and user protection, a topic we covered in our roundtable with major mailbox providers. As noted on Yahoo’s sender best practices page and in their own take on key email developments, the rollout was gradual but impactful. 

Many senders began reporting an increase in deferred messages and bounces as Yahoo’s systems scrutinized their sending practices. We also heard reports of declining open rates at Yahoo, likely due to more aggressive filtering of messages into the spam or promotions folders. 

Validity Sender Certification data gives us a unique glimpse into this period. Looking at the Validity Sender Certification Community data below, in early April we observed two interesting trends: 

1. A reduction in overall attempted volume to Yahoo. 
2. An improvement in inbox placement rates for the mail that was sent. 

This tells us that sophisticated senders were quick to react. Faced with deferrals and engagement drops, they focused their efforts, likely by trimming unengaged contacts from their lists and ensuring compliance with Yahoo’s requirements. They sent less email, but the email they sent performed better. This proactive list hygiene is a positive development, but the initial dip in volume and engagement was felt across the industry. 

Navigating a new email landscape 

Neither the Apple updates nor Yahoo’s enforcement happened in a vacuum. It’s crucial to remember that these two worlds are not mutually exclusive. A significant number of users access their Yahoo Mail accounts directly through the Apple Mail client—a fact that is especially true in the United States where, according to Validity’s 2025 Email Deliverability Benchmark Report, Yahoo holds about 21.8 percent of the market share. 

This overlap created a perfect storm for declining engagement metrics in early 2025. One plausible theory: A user’s marketing emails were first moved out of the primary line of sight by Apple’s categorization. At the same time, the underlying Yahoo account for that same user was subject to stricter enforcement, which may have pushed borderline mail into the spam folder, compounding the problem. In essence, it became harder to reach the inbox, and even when you did, it was more challenging for messages to be seen.  

Conclusion 

Email deliverability isn’t getting easier. Even if you’re a good sender, your messages are still at risk of landing in the spam folder due to changing mailbox provider requirements, AI and other technology changes.  

Navigating the complexities of the email ecosystem while monitoring your own program can seem overwhelming. But Validity’s Sender Certification program can help you get recognized as a trusted sender by mailbox providers and filtering companies, while also ensuring compliance with their changing requirements. Learn how you can join this exclusive group of reputable senders and land in more inboxes around the world!