Key takeaways ✨
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At Litmus Live 2026, we got something rare: an unfiltered look at how the inbox actually works—from the people who build it. In a session titled The Inbox Decoded: How Mailbox Providers Really Think About Email, Validity’s Tom Bartel and Guy Hanson sat down with Ross Adams from Microsoft, Dan Givol from Google, and Marcel Becker from Yahoo.
The conversation was candid, honest, and had both email marketing leaders and practitioners hanging on every word.
Watch the full session recording here and read on for a session recap.
Table of Contents
- Mailbox providers want your emails to land
- How do mailbox providers think about email?
- What being a “good sender” means in 2026
- AI is changing the inbox
- Don’t try to game the system
- AI is also making phishing more dangerous
- Sender tools: use the data you have
- The one thing that matters most
- What email marketers and marketing leaders should take away
Mailbox providers want your emails to land
Let’s start by clearing up a common misconception. Many email marketers assume mailbox providers (MBPs) are strict gatekeepers—that Gmail, Yahoo, and Microsoft are on guard against brand emails by default. But that’s simply not true.
“We love email marketers,” said Yahoo’s Marcel Becker. “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.”
Microsoft’s Ross Adams agreed: “Consumers want [marketing emails]. They’re ordering things. They want to know about various sales that are going on.”
Google’s Dan Givol added a perspective worth pausing on: “Today, your marketers are part of this webinar, but as soon as this is over, you become our consumers. Put that lens on as you communicate with your users and ask yourself, do I want to receive this?”
The nuance is that the email ecosystem has a serious noise problem. According to Marcel, roughly 90% of email in circulation is malicious. “Our job is not so much to identify the bad stuff,” he said. “It’s more to identify the good stuff for our users.”
Tom Bartel, SVP of Data Services at Validity, framed it with his two rules of deliverability: “The first rule is, as a sender, it’s not really about you—there’s ninety percent of really bad mail polluting the system. They’re not looking to punish good senders just because they feel like it. The second rule is that it is all about you. Do the fundamentals well—clear transmission, making sure the identity is correct, email authentication, DMARC. Beyond that, just send wanted mail. Don’t annoy recipients.”
How do mailbox providers think about email?
The session chat was filled with so many great questions that the speakers did not have time to answer them all. Here are a few that speakers were able to answer after the event ended:
Do mailbox providers view all emails as suspicious by default?
No, there’s no inherent bias against legitimate business email. MBPs acknowledge that most email traffic is malicious, so newer senders and domains face more scrutiny than those that have been sending engaging emails for a while. But if you’re a legitimate sender and your subscribers are excited to engage with your emails, you should be good to go.
What signals do MBPs use to evaluate senders?
Engagement is the primary trust signal. Spam complaint rates, bounce rates, unsubscribe activity, and positive interactions all feed into how a sender is evaluated. According to Validity’s 2026 Email Deliverability Benchmark Report, keeping spam complaint rates below 0.1% is now desired—down from the previously cited threshold of 0.2–0.3%.
How quickly does bad sender reputation recover?
It takes dedicated steps to change your sender reputation, not just time. Dan Givol described sender reputation as, “A backwards-looking proxy for the way that users perceive your messages.” His advice: “If you don’t like what you see, take action sooner rather than later because the deeper you get in the hole, the harder it is to get out.”
Tom Bartel echoed this with a simple mantra: “Nothing changes if nothing changes.”
How can senders reduce the spam complaints on their transactional emails?
Sorting emails according to function helps ensure the best delivery possible. MBP guidance recommends using different IP addresses for each message type. For example, you could use one IP address for account notifications, another for promotional messages, etc.
The same applies to “from addresses.” This means sales receipt messages use coming from an email like sales@example.com while promotional messages use deals@example.com. Senders should always avoid mixing different types of content in the same message. Validity has a helpful article on this topic.
What are the benefits of implementing BIMI?
BIMI adds a verified sender logo that appears next to your message in the inbox. It’s a way for inbox providers to verify information about your brand and works right alongside SPF, DMARC, and DKIM to signal to email clients that you are you.
Tom Bartel says, “Early adoption of BIMI ensures first mover advantage. While it’s likely MBPs now see upwards of 40% of their inbound commercial email volume covered by BIMI certificates, there is still a missed opportunity to stand out in the inbox in these early (now mid) days of adoption.
Beyond BIMI, MBP guidance is clear that, “Senders should use display names that are consistent, clear, and provide an accurate statement of the sender’s identity. Doing so will drive recognition and trust benefits similar to those described above. Senders should also consider implementing Apple Branded Mail,” notes Guy Hanson.
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What being a “good sender” means in 2026
There’s no shortage of advice about what makes a good email sender. The panelists identified a few very important pieces that move the needle from ok to good—or even great.
Authentication is non-negotiable
Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC) are no longer best practices—they’re requirements. Gmail, Yahoo, and Microsoft have all introduced bulk sender mandates that make authentication mandatory for high-volume senders.
As of November 2025, Gmail ramped up enforcement on non-compliant traffic. Messages that fail to meet sender requirements now experience disruptions including temporary and permanent rejections. Validity’s benchmark data shows these requirements contributed to global inbox placement rising to 87.2% in 2025—a 3.7% year-over-year improvement—although they do vary significantly by MBP, region, and industry.
For the strongest protection, set your DMARC policy to p=quarantine or ideally p=reject.
Email list hygiene matters more than ever
High unknown user rates (hard bounces) signal poor email list quality to MBPs. Validity’s benchmark data shows the average unknown user rate held at 1.46% in 2025—a figure that can climb quickly without active list maintenance.
Senders should monitor hard bounces, soft bounces, and inactive recipients—and remove invalid recipients from their lists promptly.
Engagement over volume
Relevance-sorted inboxes now prioritize emails based on user behavior, not send time. Validity’s 2026 Email Deliverability Benchmark Report notes that Gmail’s promotions tab ranks emails according to the brands users interact with most. A list full of disengaged subscribers doesn’t just waste budget, it hurts your sender reputation.
Ross Adams offered a great example from his own experience: “I ordered a wallet online, and then I got bombarded with mail. That type of experience, whilst maybe good for some people, was certainly not an expectation I had.” His point: email service providers (ESPs) and platforms should help senders understand when they’re crossing the line from helpful to overwhelming.
If you do plan to increase send volume, MBP guidance is to do so slowly. Guy Hanson has great advice: “When initiating an increase start with your most engaged users. Regularly monitor server responses, spam rate, and the sending domain’s reputation using services like Google Postmaster Tools, Yahoo’s Sender Dashboard, and Microsoft’s SNDS. If messages start bouncing or deferring, reduce the sending volume until the SMTP error rate decreases, then increase slowly again. If bounces and deferrals continue at a low volume, review individual messages to identify problems.”
Unlock 2026 inbox benchmarks now
Download Validity’s 2026 Email Deliverability Benchmark Report and learn how your inbox placement compares before your next send.
AI is changing the inbox
The single biggest theme to emerge from the panel: AI is not the enemy of email. Irrelevance is.
Dan Givol said, “We are injecting a new life into email. We’re taking all the benefits of a federated open system that lends itself to long form communication and we are 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:
- Gmail: subscription manager and Gemini integration
- Yahoo: Catch up feature
- Relevance-sorted inbox views
These tools are designed to help subscribers manage their inbox and surface what messages matter most to them. For senders whose content resonates, these features are a big benefit. For those sending generic, low-relevance messages, they’re a big reality to send messages that subscriber want to engage with.
Validity’s Q1 2026 Marketer Survey found that nearly half of marketing teams are experimenting with AI-driven inbox optimization, but fewer than one-third have a strategic approach. That gap is a real risk as MBPs increasingly act as intermediaries between brands and subscribers.
Marcel Becker kept the focus where it belongs, “Whether we use AI to amplify good or bad behavior doesn’t really matter at the end of the day. It’s a means to an end. We want senders to provide the best user experience to our mutual customers, and we want to provide the best user experience on top of that.”
Don’t try to game the system
One of the most direct moments of the session came when the conversation turned to senders attempting to manipulate AI systems.
Ross also gave an example of what not to do: hidden text embedded in emails. Marketers do this to attempt to manipulate how AI systems process the email’s information. While this isn’t a new concept for marketers, and it’s still not advised. “Just good content, sent the right way. The system will do the right thing with it,” Ross added.
Dan Givol agreed completely, “Hidden text has been leveraged in email quite a bit. As we shift into AI, we’ll see less support for hidden text. Don’t stuff your emails with something that the user doesn’t see. Think about it from your own lens: when you look at something, do you say, ‘this doesn’t look right? Is this AI? Am I being spoofed?’ If we see that you’re not trying to trick the user, but you’re trying to trick our system, then we will take enforcement action on it.”
This also applies to so-called “warming services” that simulate engagement, and vendors who claim they can guarantee primary tab placement. As Tom Bartel noted, “These reputation systems and algorithms are complex and dynamic. They’re not binary switches.” Anyone selling certainty without effort should give senders pause.
AI is making phishing more dangerous
The same capabilities that help marketers personalize at scale are being used by bad actors to craft more convincing fraudulent emails. Ross Adams explained that he doesn’t predominately see AI crafting the initial message, but in automating the follow-through once someone falls for a scam. “They don’t have to deal with that manually anymore. Now [attackers] can automate the response back to get all the details they need.”
For legitimate brands, this creates both a responsibility and an opportunity. When phishing emails are increasingly hard to distinguish from real marketing messages, authentication and visual identity signals like BIMI become part of your customer protection strategy—not just your email deliverability strategy.
Dan Givol put it plainly, “Help us identify you as a good actor by doing all the things that will make you identifiable. As we shift into this larger field of threats that are going to be easier to put together, do your part by identifying yourself.”
Sender tools: use the data you have
Each major MBP has invested in tools to help senders understand their performance:
- Google Postmaster Tools (now v2, with a Pass/Fail Compliance dashboard)
- Yahoo Sender Hub
- Microsoft SNDS
Ross Adams noted that Microsoft is actively working on expanding SNDS, with more domain-level visibility on the way. It’s their way of making sure that small senders—doctor’s offices, nonprofits, local businesses—do not get overlooked because they don’t understand how email really works. “The number of doctor surgeries that try and send me an appointment that never arrives because it fails authentication,” he said. “As a community, we should do a little bit more to make sure those small senders are being taken care of.”
The one thing that matters most
Near the close of the session, each panelist was asked: if a sender could do just one thing consistently well over the next year to ensure their email is wanted by users, what should it be?
- Ross Adams: “Help the small senders, fight any abuse in the system, focus on customers.”
- Marcel Becker: “Send email people want. Put yourself into the receiver’s shoes. Ask yourself, is this something I would want to receive? If the answer is no, don’t do it.”
- Dan Givol: “Obsess over the numbers each of our platforms gives you to know where you stand.”
- Tom Bartel: “Set and meet expectations with your customer for your email relationship with them.”
Takeaways for email marketers and marketing leaders
For email practitioners: the technical fundamentals like authentication, list hygiene, and monitoring aren’t background tasks. They’re the foundation everything else is built on. If those aren’t in place, no amount of creative excellence, segmentation, or send-time optimization will compensate.
For marketing leaders: inbox placement is a revenue issue, not just a technical one. Validity’s 2026 Email Deliverability Benchmark Report found that the average global inbox placement rate in 2025 was 87.2%—meaning roughly 13% of email never reaches its intended destination. At scale, that gap has significant impact on campaign ROI, customer engagement, and brand trust.
The inbox has never been more complex. It’s also never been more rewarding for brands that send email people actually want to receive.
Watch the full session recording here.
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Lindsey is a Sr. Content Marketing Manager at Validity.
