Do inbox providers share individual sender reputation scores with each other?

No, generally not. Each major inbox provider like Google Microsoft Yahoo uses its own proprietary algorithms and user feedback to determine your sender reputation and email placement. They do not share specific deliverability metrics or sender scores with their competitors.

What type of data, if any, do inbox providers share?

While they don't share deliverability data, inbox providers do often collaborate on sharing threat intelligence . This includes information about known malicious IP addresses, botnets, phishing attempts, and other widespread spam or security threats. This type of data sharing is for the collective good of internet security, not for evaluating individual marketing or transactional email performance.

If data isn't shared, why might my deliverability improve across all providers at once?

If you see improvements in deliverability across multiple providers, it's typically due to the positive impact of implementing universal email best practices . Cleaning your email list, improving content relevance, ensuring strong authentication (SPF, DKIM, DMARC), and maintaining consistent sending volume will naturally improve your overall sender health, which benefits your reputation with all providers, even if they don't share data directly. Additionally, some smaller providers might use the same backend infrastructure (e.g., Yahoo previously handled AT&T mail), leading to correlated performance.

Why do deliverability rates vary significantly between different inbox providers?

Each provider has its own distinct spam filtering criteria based on its user engagement and specific security policies. For example, Gmail might prioritize user interactions, while Yahoo (and AOL ) might have stricter content or authentication requirements. This is why a single email campaign can have varying inbox placement rates across different destinations.

Do inbox providers share email deliverability data with each other? - Sender reputation - Email deliverability - Knowledge base

One of the most persistent questions in email deliverability is whether major inbox providers (like Gmail, Outlook, or Yahoo) actually share data with each other. It's a common assumption that if your emails are landing in the spam folder at one provider, others might somehow be privy to that information, leading to widespread delivery issues. This idea stems from the intuitive thought that security and anti-spam efforts would benefit from such a collective intelligence network. However, the reality of how these providers operate is more nuanced than that.

I’ve encountered this question many times, and it often comes from senders observing unexpected fluctuations in their email performance across different domains. For instance, you might improve your engagement at one major mailbox provider, only to see a positive ripple effect at seemingly unrelated services like Comcast or Hotmail. This can understandably lead to speculation about shared data.

The short answer is no, not in the way most marketers think. Inbox providers primarily make deliverability decisions independently, based on their own proprietary algorithms and the interactions of their unique user base. They do not typically share granular sender reputation scores or specific deliverability metrics like bounce rates or open rates with their competitors.

How inbox providers evaluate senders

Each major inbox provider (also known as an Internet Service Provider or ISP) operates with its own distinct set of rules and algorithms to filter incoming email. These systems are incredibly complex, analyzing hundreds of signals to determine if an email reaches the inbox, the spam folder, or is rejected entirely. They are constantly evolving to combat new spamming techniques and ensure the best experience for their users.

Your sender reputation, therefore, is largely specific to each provider. A good reputation with

Gmail doesn't automatically translate to the same standing with

Outlook or

Yahoo. Each one independently assesses your sending behavior, engagement metrics, and compliance with their specific policies. To understand more about how this works, you can explore why email deliverability differs across mailbox providers.

Key factors that each provider considers include sender reputation (based on IP and domain), engagement (opens, clicks, replies), complaint rates, spam trap hits, and authentication protocols like SPF, DKIM, and DMARC. These individual evaluations are crucial because each provider wants to protect its own users and maintain a clean inbox environment specific to their service. For instance,

Google Postmaster Tools provides a direct view of your reputation solely with Google.

Understanding the individual evaluation process

Independent Filters: Each provider maintains its own spam filters and reputation systems, built to protect their specific user base from unwanted mail. Your performance with Microsoft Outlook is distinct from your standing with AOL.
User Engagement Data: They analyze how their users interact with your emails, including opens, clicks, deletions, and whether messages are moved to or from the spam folder. This feedback directly shapes your individual sender reputation for that provider.
Privacy Concerns: Sharing user-specific data or detailed sender reputation metrics across providers would raise significant privacy concerns and legal complexities.

The concept of data siloing

The principle of data siloing is fundamental to how most inbox providers operate their deliverability systems. Each provider maintains its own walled garden, so to speak, where its algorithms make independent judgments about incoming mail. This approach allows them to tailor their spam filtering and inbox placement rules specifically to their user base and their unique threat landscape.

There are several compelling reasons for this independent operation. Firstly, privacy is a paramount concern. Sharing sensitive data about sender performance or user engagement could be seen as a violation of user privacy and could open providers up to significant regulatory and legal challenges. Secondly, it's a matter of competitive advantage. Each provider invests heavily in developing sophisticated filtering technologies, and sharing this proprietary data would dilute their competitive edge. Finally, user bases differ; what one group of users considers spam, another might welcome, meaning a universal reputation score might not be effective or desired.

While this siloing can sometimes make it challenging for senders to diagnose deliverability issues across different providers (as each might treat your mail differently), it ensures that your reputation is earned individually, rather than being broadly impacted by your standing with a single service. This means if your spam complaint rates are siloed by provider, it won't necessarily doom your deliverability everywhere else.

Perceived data sharing

Many senders believe that if their emails are hitting the spam folder at one major provider, like

Gmail, this negative signal is somehow transmitted to others, such as

Yahoo Mail or

Outlook.com. This fear often leads to a focus on broad, sweeping changes to improve deliverability across the board, based on a single provider's performance.

Potential outcomes of perceived sharing

Generalized Blacklisting: Belief that a blocklist (or blacklist) at one provider would immediately spread to others.
Universal Reputation Score: Expectation of a single, shared sender reputation influencing all major inbox providers.
Cross-Provider Punishment: If a sender is marked as spam by users of one service, other services would somehow know and also filter their mail more aggressively.

Actual independent evaluation

In reality, major inbox providers like

AT&T,

Verizon, and

Comcast maintain independent systems for assessing sender reputation and deliverability. Their filtering decisions are based on data collected from their own users and internal algorithms. While commonalities in good sending practices exist, direct sharing of individual sender performance data is not standard practice.

Reasons for independent operation

Proprietary Algorithms: Each provider invests heavily in unique spam-filtering technologies, which are considered trade secrets.
User Trust & Privacy: Sharing user-specific data or detailed sender reputations could undermine user trust and violate privacy regulations.
Competitive Differentiation: Their ability to deliver relevant mail is a core part of their service offering and a key differentiator in the market.

What data is shared (and why)

While direct deliverability data is not shared, there are instances where mailbox providers collaborate or have underlying connections that can create the *perception* of shared data. The most significant area of collaboration is in combating threats. Providers often share threat intelligence about known malicious actors, botnets, phishing campaigns, and IP addresses engaged in widespread abuse. This is done to protect the broader internet ecosystem, not to influence individual sender reputation scores.

For example, if an IP address is identified as a source of malware or a spam botnet, this information might be shared among security teams at different providers. This helps them quickly block or mitigate widespread attacks. It's a critical aspect of internet security, distinct from whether your marketing newsletter lands in the inbox. You can learn more about how email blacklists work to understand this aspect better.

Another point to consider is the consolidation of backend services. Historically, some smaller domains or ISPs have outsourced their email infrastructure to larger providers. For instance,

Yahoo (and by extension

AOL) has provided email services for domains like att.net and sbcglobal.net. If you improve your sending practices to

Yahoo, you might see a corresponding lift in these associated domains, not because data is shared between independent entities, but because they are managed by the same underlying system. This is an important distinction when assessing how complaint rates affect Yahoo and AOL deliverability.

Data Type	Shared Among Providers?	Purpose
Sender Reputation Scores	No	Proprietary assessment of individual sender quality.
Engagement Data (Opens, Clicks)	No	User-specific feedback for individual filtering decisions.
Spam Complaints	No, generally via Feedback Loops.	To inform sender reputation and allow senders to manage unsubscribes.
Threat Intelligence (Malicious IPs, Botnets)	Yes	Collective defense against widespread cyber threats.

Factors influencing perceived cross-provider improvements

So, if providers don't directly share deliverability data, why might a sender observe improved performance across multiple, seemingly unrelated domains after making changes for just one? This often comes down to the holistic nature of good email sending practices.

When you implement best practices to improve your standing with one provider, these practices inherently benefit your overall email program. For example, if you focus on cleaning your email list to reduce bounces and inactive users, this leads to better engagement rates universally. If you improve your content relevance and personalization, it’s likely to resonate better with all your subscribers, regardless of their email provider.

Similarly, ensuring proper email authentication (SPF, DKIM, and DMARC) is a fundamental best practice that all providers value. Strengthening these records doesn't just appease

Google and

Yahoo, it signals legitimacy to every mailbox provider. These foundational improvements create a healthier sending environment for your domain and IPs, which then positively influences how all providers view your email. Learn how to boost email deliverability rates through technical solutions.

The perceived shared improvement is often a testament to improving your overall sender reputation and list quality, rather than direct data sharing between competing entities. When your fundamental email practices improve, the beneficial effects naturally extend across all destinations.

Views from the trenches

Best practices

Maintain a clean and engaged email list to naturally improve deliverability across all providers.

Implement strong authentication protocols like SPF, DKIM, and DMARC consistently for universal trust.

Monitor individual provider feedback loops and postmaster tools to track performance with each service.

Segment your audience effectively to send highly relevant content, improving engagement rates.

Common pitfalls

Assuming that good deliverability at one provider automatically means good deliverability at all others.

Ignoring specific feedback from individual mailbox providers (e.g., Google Postmaster Tools warnings).

Failing to clean inactive subscribers, which can drag down overall engagement metrics.

Relying solely on open rates as a measure of inbox placement, which can be misleading.

Expert tips

Understand that while direct data sharing is rare, foundational improvements cascade positively.

Be aware of shared backend services, such as Yahoo handling AT&T email, which can link performance.

Recognize that providers prioritize their users' experience, leading to independent filtering criteria.

Focus on the long game: consistent, healthy sending practices build lasting reputation everywhere.

Expert view

Expert from Email Geeks says inbox providers are very clear that just because one provider likes your mail, it doesn't mean another will.

December 2, 2019 - Email Geeks

Expert view

Expert from Email Geeks says there are significant privacy implications regarding sharing user data with third parties.

December 2, 2019 - Email Geeks

The independent nature of email deliverability

The idea that inbox providers share detailed email deliverability data with each other is a common misconception. In reality, major providers like

Gmail

Outlook

Yahoo operate independently, each with its own algorithms for assessing sender reputation and determining inbox placement. This independence is driven by privacy concerns, competitive advantage, and the unique characteristics of their user bases.

While there's no direct sharing of deliverability performance, collaboration occurs on a higher level, specifically for threat intelligence related to malicious activities like botnets and phishing. Any observed improvements in deliverability across multiple providers are typically a result of implementing universal email best practices. These practices, such as maintaining a clean list, ensuring strong authentication, and sending engaging content, naturally elevate your sender reputation across the board. Focusing on these core elements is the most effective way to ensure your emails consistently reach the inbox.