How MBPs Think About Email: Google, Yahoo, & Microsoft

At the highly anticipated Litmus Live 2026 conference, a landmark session titled "The Inbox Decoded: How Mailbox Providers Really Think About Email" offered an unprecedented, unfiltered glimpse into the operational philosophies of the world’s leading mailbox providers (MBPs). This candid discussion featured industry titans Ross Adams from Microsoft, Dan Givol from Google, and Marcel Becker from Yahoo, alongside Validity’s Tom Bartel and Guy Hanson, drawing a rapt audience of email marketing leaders and practitioners eager to understand the evolving landscape of email deliverability. The insights gleaned from this panel underscored a fundamental shift in how MBPs operate, emphasizing user experience, robust authentication, and the burgeoning influence of artificial intelligence.

The core message resonating from the panel was clear: Mailbox Providers are not inherently adversarial gatekeepers but rather diligent guardians against a deluge of malicious content, actively striving to ensure legitimate, wanted emails reach their intended recipients. Marcel Becker of Yahoo articulated this sentiment, stating, "We love email marketers. That’s what consumer email is about. At the end of the day, it’s very simple: send mail users want. They decide what that is, not us." This perspective was echoed by Microsoft’s Ross Adams, who highlighted consumer demand for marketing emails, particularly for order confirmations and sales notifications. Dan Givol of Google urged marketers to adopt a consumer-centric lens, asking themselves if they would personally want to receive the emails they send.

Navigating the Deluge: MBPs as Curators, Not Gatekeepers

A pervasive misconception among email marketers is that MBPs default to viewing all commercial email with suspicion. The panel firmly debunked this, clarifying that while the email ecosystem grapples with an immense "noise problem" – with roughly 90% of email traffic being malicious – the primary objective of MBPs is to identify and deliver "good" mail. Tom Bartel, SVP of Data Services at Validity, encapsulated this with his two rules of deliverability: first, that the sender is not the sole focus amidst the vast ocean of bad mail, and second, that it is all about the sender’s adherence to fundamentals like clear transmission, correct identity, and robust email authentication (including DMARC). Beyond these technical prerequisites, the paramount rule remains: send wanted mail and avoid annoying recipients.

Newer senders and domains naturally face increased scrutiny due to the high volume of malicious traffic originating from unestablished sources. However, for legitimate senders consistently delivering engaging content, there is no inherent bias. The overarching goal for MBPs is to foster a healthy email environment where users receive valuable communications and are protected from spam and phishing.

The Evolving Science of Sender Evaluation

Mailbox Providers employ sophisticated algorithms to evaluate senders, with "engagement" emerging as the preeminent trust signal. This encompasses a holistic view of subscriber interactions, including positive actions like opens, clicks, and replies, alongside negative indicators such as spam complaints, bounce rates, and unsubscribe activity. Validity’s 2026 Email Deliverability Benchmark Report highlighted a critical shift: keeping spam complaint rates below 0.1% is now the desired benchmark, a tighter threshold than the previously cited 0.2-0.3%. This adjustment underscores the increasing sensitivity of MBP systems to user dissatisfaction.

Sender reputation, as described by Dan Givol, is a "backwards-looking proxy for the way that users perceive your messages." This implies that reputation is built and eroded over time based on sustained behavior. Consequently, recovering from a damaged sender reputation requires deliberate and consistent corrective action, not merely the passage of time. As Tom Bartel succinctly put it, "Nothing changes if nothing changes." Marketers must proactively address issues like high complaint rates or low engagement rather than waiting for reputation to magically improve.

Optimizing for Delivery: Beyond Promotional Content

A nuanced area of concern for many marketers is the deliverability of transactional emails – messages crucial for customer experience, such as order confirmations, shipping updates, and account notifications. MBPs strongly recommend segmenting email types to ensure optimal delivery. This guidance suggests using distinct IP addresses and "from" addresses for different message categories. For instance, [email protected] for receipts and [email protected] for promotions helps MBPs categorize and prioritize mail streams, reducing the likelihood of critical transactional messages being flagged due to promotional content issues. Mixing content types within a single message is also discouraged, as it can confuse filtering algorithms and negatively impact deliverability. Validity offers comprehensive resources on tackling transactional email complaints, emphasizing the importance of this segmentation.

Furthermore, implementing Brand Indicators for Message Identification (BIMI) is gaining traction as a vital component of sender identity and trust. BIMI allows a verified sender logo to appear alongside messages in the inbox, acting as a visual cue of authenticity. This works in conjunction with foundational authentication protocols like SPF, DMARC, and DKIM to signal a brand’s legitimate identity to email clients. Tom Bartel noted that early adoption of BIMI offered a "first mover advantage," and while MBP coverage of BIMI certificates is now upwards of 40% of inbound commercial email, a significant opportunity still exists for brands to stand out. Beyond BIMI, MBPs advocate for consistent, clear display names that accurately reflect the sender’s identity, fostering recognition and trust. Guy Hanson also highlighted the benefits of implementing Apple Branded Mail for enhanced visual branding within Apple’s email ecosystem.

The Imperatives of a "Good Sender" in 2026

The panel identified several non-negotiable requirements for establishing and maintaining a strong sender reputation in the current email climate:

1. Authentication is Non-Negotiable: Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC) have transcended best practice to become mandatory requirements. Google, Yahoo, and Microsoft have all implemented bulk sender mandates that compel high-volume senders to adopt these protocols. As of November 2025, Gmail significantly ramped up enforcement on non-compliant traffic, leading to disruptions, including temporary and permanent rejections. This stringent enforcement has contributed to a global inbox placement rate of 87.2% in 2025, a 3.7% year-over-year improvement, as per Validity’s benchmark data, though performance varies by MBP, region, and industry. For the highest level of protection and trust, setting a DMARC policy to p=quarantine or, ideally, p=reject is strongly advised.

2. Email List Hygiene Matters More Than Ever: High unknown user rates, commonly known as hard bounces, are a strong indicator of poor list quality to MBPs. Validity’s data for 2025 showed the average unknown user rate at 1.46%, a figure that can rapidly escalate without proactive list maintenance. Dan Givol stressed the criticality of list hygiene, warning that sending messages to disengaged or invalid recipients inevitably leads to spam complaints. Marketers must diligently monitor hard bounces, soft bounces, and inactive recipients, promptly removing invalid addresses from their databases.

3. Engagement Over Volume: Modern, relevance-sorted inboxes prioritize emails based on individual user behavior rather than mere send time. Google’s Promotions tab, for instance, ranks emails according to the brands with which users interact most frequently. This means that a large list filled with disengaged subscribers not only wastes marketing budget but actively harms sender reputation. Ross Adams shared a personal anecdote about being "bombarded" after a single purchase, illustrating how excessive, unwanted volume can quickly turn a helpful interaction into an overwhelming one. Email service providers (ESPs) and platforms bear a responsibility to help senders identify when they are crossing this line. When increasing send volume, MBP guidance recommends a gradual approach, starting with the most engaged users and closely monitoring server responses, spam rates, and sending domain reputation through tools like Google Postmaster Tools, Yahoo’s Sender Dashboard, and Microsoft’s SNDS. Any increase in bounces or deferrals should prompt a reduction in volume until error rates stabilize.

AI’s Transformative Impact on the Inbox

Perhaps the most significant theme to emerge from the panel was the role of artificial intelligence. The consensus was clear: AI is not the enemy of email; irrelevance is. Dan Givol articulated this vision, stating, "We are injecting a new life into email… supercharging it with technology that was designed exactly to solve the problem of what do I need to do next."

In 2025, MBPs introduced a wave of AI-powered inbox features designed to empower subscribers and enhance their email experience. These innovations include AI-driven email summaries, smart replies, priority inbox sorting based on predicted user relevance, and advanced content categorization. For senders whose content genuinely resonates with recipients, these features offer a significant advantage, increasing visibility and engagement. Conversely, for those sending generic, low-relevance messages, AI acts as an efficient filter, pushing such content to the background or directly to spam.

Validity’s Q1 2026 Marketer Survey revealed a critical disparity: while nearly half of marketing teams are experimenting with AI-driven inbox optimization, fewer than one-third have a strategic, cohesive approach. This "gap" represents a substantial risk, as MBPs increasingly act as intelligent intermediaries between brands and subscribers. Marcel Becker underscored that AI is merely a "means to an end," emphasizing that the ultimate goal remains providing the best user experience to mutual customers.

The Perils of Gaming the System

A candid moment in the session addressed attempts by senders to manipulate AI systems. Ross Adams issued a stern warning: "Gaming is going to be your worst enemy when it comes to these AI advancements we’re making." He cited examples like hidden text embedded in emails – a tactic used to manipulate how AI systems process message information. While not a new concept in marketing, such practices are strongly advised against. Adams stressed that MBPs are actively looking for such manipulations, viewing them similarly to malicious attacks. "Just good content, sent the right way. The system will do the right thing with it," he affirmed.

Dan Givol wholeheartedly agreed, noting that while hidden text has been used in email for some time, AI’s advent will likely diminish its efficacy. He urged marketers to consider the user’s perspective: if content looks suspicious or manipulative, it will trigger flags within AI systems. Attempts to "trick our system" will result in enforcement actions. This warning extends to "warming services" that simulate engagement and vendors who guarantee primary tab placement, as Tom Bartel noted, "These reputation systems and algorithms are complex and dynamic. They’re not binary switches." Any promise of certainty without genuine effort should raise red flags for senders.

AI and the Escalating Threat of Phishing

The same AI capabilities that enable sophisticated personalization for legitimate marketers are unfortunately being leveraged by malicious actors to craft more convincing and dangerous fraudulent emails. Ross Adams highlighted that AI is not predominantly used to craft initial phishing messages but rather to automate the follow-through once a victim falls for a scam. This automation makes it easier for attackers to extract necessary details without manual intervention, significantly amplifying the threat.

This heightened phishing risk creates both a profound responsibility and a strategic opportunity for legitimate brands. When fraudulent emails become increasingly difficult to distinguish from authentic marketing messages, robust authentication protocols and visual identity signals like BIMI transition from mere deliverability best practices into essential components of a brand’s customer protection strategy. Dan Givol plainly stated, "Help us identify you as a good actor by doing all the things that will make you identifiable." In an era of escalating AI-powered threats, self-identification through strong authentication is paramount.

Leveraging Mailbox Provider Tools for Success

Recognizing the complexity of the email ecosystem, each major MBP has invested in providing senders with tools to understand and improve their performance. These include Google Postmaster Tools, Yahoo’s Sender Dashboard, and Microsoft’s Smart Network Data Services (SNDS). Marcel Becker emphasized the value of these resources, stating, "I personally believe in providing meaningful and actionable data in a privacy-conscious way to senders. Stop trusting random guys on the Internet. Use the tools we actually provide because that data is a little bit more meaningful."

Ross Adams noted that Microsoft is actively expanding SNDS to offer greater domain-level visibility. This initiative aims to support smaller senders – like doctor’s offices, non-profits, and local businesses – who may lack the technical expertise of larger enterprises but whose legitimate communications are equally vital. Adams highlighted the common problem of essential messages failing authentication, underscoring a collective responsibility within the email community to ensure these small senders are not overlooked. Tom Bartel reinforced this collaborative spirit, framing it as "teamwork, not opposition." He asserted that MBPs provide this data to help senders improve, driving mutual satisfaction and successful inbox placement.

The Singular Imperative: Sending Wanted Mail

As the session concluded, each panelist was asked to identify the single most important action a sender could consistently execute over the next year to ensure their email is wanted by users. The resounding consensus underscored the overarching theme of the discussion: Send relevant, engaging, and genuinely desired content. This encompasses everything from respecting user preferences and managing expectations to delivering value and maintaining a clean, authenticated sending posture.

Key Takeaways for Email Marketers and Leaders

For email practitioners, the session solidified that technical fundamentals – robust authentication (SPF, DKIM, DMARC), rigorous list hygiene, and diligent monitoring of performance metrics – are not auxiliary tasks but the bedrock upon which all successful email marketing is built. Without these foundational elements in place, even the most creative campaigns, sophisticated segmentation, or optimized send times will fail to reach their full potential.

For marketing leaders, the implications are stark: inbox placement is fundamentally a revenue issue, not merely a technical one. Validity’s 2026 Email Deliverability Benchmark Report’s finding of an average global inbox placement rate of 87.2% in 2025 means that approximately 13% of all email never reaches its intended destination. At scale, this gap has a profound and measurable impact on campaign ROI, customer engagement, and ultimately, brand trust.

The email inbox has undoubtedly grown in complexity, particularly with the integration of advanced AI. However, this complexity also ushers in an era of unprecedented opportunity for brands that commit to delivering truly wanted emails. By embracing the principles of user-centricity, technical diligence, and authentic engagement, marketers can navigate this evolving landscape and reap significant rewards. The full session recording is available for those seeking deeper insights into these critical discussions.