Summary
It can be perplexing when your Sender Score appears low, yet your email delivery rate remains high. This discrepancy often arises because Sender Score, while a known metric, does not encompass all factors internet service providers (ISPs) use to evaluate sender reputation. A high delivery rate primarily indicates that emails are not bouncing, but it doesn't guarantee inbox placement, which is where a low Sender Score might hint at hidden issues. ISPs consider a multitude of data points, including engagement, spam complaints, and blocklist (or blacklist) presence, which may not be fully reflected in a simple delivery rate.
Key findings
- Sender Score limitations: Sender Score is a proprietary metric and does not represent the full spectrum of reputation signals used by major mailbox providers. Many large ISPs (e.g., Gmail, Outlook) do not directly use Sender Score data to determine inbox placement. Learn more about factors influencing email deliverability and Sender Score.
- Delivery vs. inboxing: A high delivery rate means your emails are accepted by recipient servers, but not necessarily placed in the inbox. They might be routed to spam folders, which a low Sender Score could indicate.
- Bounce nuances: Even a small percentage of bounces, particularly hard bounces or those from specific providers (e.g., Yahoo/AOL/Verizon, which often host many legacy accounts), can disproportionately impact your sender reputation, especially if those providers are not 'partners' with Sender Score. Understand email delivery rate and how to improve it.
- IP type: If you are using a shared IP address, your Sender Score may be influenced by the sending practices of other users on that IP, irrespective of your own excellent delivery practices.
Key considerations
- Alternative reputation tools: Focus on reputation tools provided by major ISPs, such as Google Postmaster Tools or Outlook's Smart Network Data Services. These provide direct feedback from the providers that matter most for inbox placement.
- Monitor engagement metrics: Pay close attention to open rates, click-through rates, and spam complaint rates. Low engagement or high complaints, even with a high delivery rate, signal potential inboxing issues to ISPs.
- Address all bounces: Investigate even small percentages of bounces. Identify common domains or specific bounce types to understand if particular providers are blocking your messages. Regularly clean your lists to remove invalid addresses, which can reduce hard bounces and improve overall list health.
- Implement authentication: Ensure your email authentication protocols like SPF, DKIM, and DMARC are correctly configured. DMARC, especially with a enforcement policy like p=reject, helps prevent domain spoofing, which can negatively impact your sender reputation even if the fraudulent emails aren't sent from your IP. This is crucial for avoiding blocklist issues and improving DMARC protection.
What email marketers say
Email marketers often find themselves in a challenging position when their Sender Score is low despite seeing high delivery rates. This paradox highlights a common misunderstanding: delivery isn't the same as inbox placement. While messages might be accepted by servers, they often end up in spam or junk folders without the sender's knowledge. Marketers frequently note that Sender Score might not be the most reliable indicator, emphasizing the importance of diverse metrics and direct ISP feedback to truly gauge reputation and ensure emails reach the inbox.
Key opinions
- Sender Score's relevance: Many marketers question the direct correlation between Sender Score and actual inbox placement, noting that they've seen poor Sender Scores with good delivery and vice versa. Some consider it an outdated or unreliable metric for modern deliverability.
- Impact of minor bounces: Even a very low bounce rate (less than 1%) can significantly impact Sender Score, especially if those bounces are hard bounces or originate from domains controlled by providers that highly weigh such signals.
- Shared IP challenges: If using a shared IP, reputation issues could stem from other senders' activities rather than your own, blending data and obscuring the true cause of a low score.
- Verizon/AOL/Yahoo challenges: These domains, now largely managed by Yahoo, are often cited as particularly challenging for deliverability due to their large number of legacy accounts and stringent filtering. Marketers often consider suppressing these recipients during deliverability dips. Learn why email sender reputation is crucial for deliverability.
Key considerations
- Focus on ISP postmaster tools: Prioritize monitoring Google Postmaster Tools and other ISP-specific feedback loops. These offer direct insights into how major providers perceive your sending practices. This helps to accurately evaluate your sender score and improve inbox placement.
- Investigate bounce patterns: Even with a low bounce rate, analyze the specific domains causing bounces. Small domains with many rejections can signal issues with specific providers, even if overall numbers are low. Monitor for timeout bounces, particularly with providers like Yahoo/Verizon.
- Consider email list age and warming: Older lists or those acquired from other sources may contain more inactive or problematic addresses that require careful warming or suppression, especially when using new IPs or resuming sending after a pause.
- Utilize email validation: Regularly validate your email lists to reduce hard bounces and minimize sending to invalid or risky addresses, even if you have a low bounce rate. This proactive approach helps maintain a healthy sending reputation.
Marketer view
Marketer from Email Geeks doesn't believe anything is being missed. Even a very low bounce rate (sub-1%) having a large impact on Sender Score might be unusual or a 'scare tactic,' suggesting that the metric itself may not always correlate with actual delivery.
Marketer view
Marketer from Email Geeks indicates that they stopped trusting Sender Score a decade ago because it often showed poor correlation with actual email delivery outcomes. They observed instances where clients with low scores had great delivery, while others with high scores experienced terrible delivery.
What the experts say
Experts in email deliverability offer nuanced perspectives on why a low Sender Score might coexist with a high delivery rate. They frequently point out that Sender Score is one of many signals, and not always the most critical one, for major ISPs. A high delivery rate merely means the email wasn't rejected outright. However, a low Sender Score can highlight underlying issues like hidden filtering to spam or subtle reputation damage. Experts emphasize leveraging ISP-specific feedback, monitoring engagement, and robust authentication (e.g., DMARC) to get a clearer picture of true inbox placement.
Key opinions
- Sender Score vs. ISP reputation: Top mailbox providers (like Gmail, Outlook, Yahoo) are not Sender Score partners, meaning its data does not directly influence their filtering decisions. Therefore, a low Sender Score might not significantly impact your actual inbox placement if your performance with major ISPs is strong. This is a common point when discussing how relevant Sender Score is to email deliverability.
- Shared IP influence: For shared IP addresses, Sender Score data blends all activity. Issues from other senders on the same IP could cause your score to be low, even if your own sending practices are good.
- Spoofing concerns: Bad actors spoofing your sending domain can cause 'Sender Rejected' spikes in reports. While this generally shouldn't affect your legitimate IP's score, it highlights the importance of DMARC implementation to mitigate brand abuse and potential reputation damage.
- Smaller provider issues: Sometimes smaller email providers or Sender Score partners may have internal issues that contribute to message rejections, impacting your score despite good sending practices.
Key considerations
- Implement DMARC: DMARC is crucial for monitoring email authentication and detecting domain spoofing. Experts strongly recommend moving to an enforcement policy (p=reject) once confident in your legitimate email flows to protect your brand and domain reputation. This helps prevent issues that could explain a low email sender score.
- Address Yahoo/AOL/Verizon deliverability: While challenging, understanding and adhering to postmaster best practices for these domains is vital. Timeouts, in particular, can be a common bounce reason that might require careful volume management during warming or for re-engaging older lists.
- Understand ISP-specific metrics: Shift focus from generalized scores to specific ISP metrics, such as spam complaint rates and reputation dashboards within their postmaster tools, to truly assess inbox placement. For example, Mailgun’s resources discuss how sender reputation impacts inbox placement.
- Proactive email hygiene: Even with a high delivery rate, routinely validate email lists and actively manage bounces (especially hard bounces and timeouts) to prevent minor issues from compounding into significant deliverability problems with specific providers.
Expert view
Expert from Email Geeks confirms that Sender Score alone may not be the definitive measure of deliverability. They suggest that if an IP's Sender Score is low, but the delivery rate is high, it indicates that the metric might not be capturing the full picture of factors impacting inbox placement.
Expert view
Expert from Email Geeks warns that Sender Score provides feedback only on dedicated sending IP addresses. If you're using shared IP addresses, the data is blended, and issues might stem from other users' activities, not your own sending.
What the documentation says
Official documentation from various sources, including Sender Score's creators, provides insights into how the score is calculated and its intended purpose. While it measures reputation based on specific metrics like rejections and spam traps, it's crucial to understand that it represents only a subset of the vast data points ISPs use. Documentation often emphasizes factors such as email volume consistency, bounce rates, spam complaint rates, and participation in feedback loops as critical components of sender reputation. This highlights that a high delivery rate does not automatically guarantee a high Sender Score or, more importantly, optimal inbox placement.
Key findings
- Sender Score calculation: Sender Score is primarily based on a 30-day rolling average of metrics related to an IP address's sending behavior, including complaint rates, spam trap hits, rejected emails, and external blocklist (or blacklist) listings. The goal is to provide a predictive measure of reputation.
- Proprietary algorithm: The exact algorithm for Sender Score is proprietary, meaning the specific weighting of factors is not publicly disclosed. This can make it challenging to pinpoint why a score is low if other metrics appear good. This relates to Sender Score reporting inaccurate data.
- Spam traps and blocklists: Hits on spam traps and being listed on blocklists (or blacklists) are high-impact factors that can severely depress a Sender Score, regardless of a high delivery rate for other emails. For more information on blocklists, read an in-depth guide to email blocklists.
- IP vs. domain reputation: While Sender Score focuses on IP reputation, domain reputation is increasingly critical for ISPs. Even with a good IP score, a poor domain reputation (e.g., due to DMARC failures or historical abuse) can lead to inboxing issues. Mailchimp explains how email sender reputation affects deliverability.
Key considerations
- Holistic reputation management: Do not rely solely on Sender Score. Implement comprehensive monitoring that includes ISP-specific feedback loops, engagement metrics (opens, clicks, unsubscribes), and direct complaint rates. A low Sender Score might indicate a need to troubleshoot a dropping email sender score.
- Identify 'Sender Rejected' causes: If 'Sender Rejected' is a high impact measure, investigate if these are hard bounces, which indicate invalid addresses, or temporary rejections that could signal throttling or other filtering actions by recipients.
- Proactive list hygiene: Regularly clean your email lists to remove inactive or invalid addresses, reducing bounce rates and the risk of hitting spam traps. This also helps improve your overall email deliverability. For general deliverability, see EmailTooltester's best practices.
- Understand ISP-specific requirements: Each ISP has unique filtering mechanisms and reputation metrics. Adhering to their specific postmaster guidelines and best practices is often more impactful than a generalized score.
Technical article
Documentation from Return Path (Validity) describes Sender Score as a measure of an IP address’s reputation, ranging from 0 to 100. It is based on a 30-day rolling average of various metrics that affect deliverability, including complaint rates, spam trap hits, and direct rejections.
Technical article
Documentation from Mailgun explains that email sender reputation is determined by various factors, including the sender's IP address, domain, the content of the emails, and the level of engagement from recipients, all of which contribute to or detract from inbox placement.
Related resources
12 resources
Related pages
What factors influence email deliverability and how does SenderScore work?
Why is SenderScore showing inaccurate data or low scores?
Why has my sender score dropped and what can I do about it?
How relevant is sender score to email deliverability?
How can I best evaluate my sender score to improve inbox placement?
A simple guide to DMARC, SPF, and DKIM
Why your emails are going to spam in 2024 and how to fix it
Boost email deliverability rates: Technical solutions from top performing senders
An in-depth guide to email blocklists
Understanding and troubleshooting DMARC reports from Google and Yahoo
