Why has my Sender Score dropped despite no changes in other metrics?
Matthew Whittaker
Co-founder & CTO, Suped
Published 26 Jun 2025
Updated 18 Aug 2025
9 min read
It can be perplexing when your sender score takes a nosedive, yet your other key email metrics, such as open rates, click-through rates, and bounce rates, appear to remain stable. This scenario often leaves email marketers and deliverability professionals scratching their heads. While it might seem counterintuitive, a significant drop in a reputation metric like Sender Score, even without immediate changes in other reported metrics, is a clear signal that something is amiss.
The discrepancy often lies in the nature of Sender Score itself and how different mailbox providers (like Google and Yahoo) evaluate incoming mail. Sender Score is a metric provided by Validity, based on data collected from their network of email receivers and spam traps. It provides an indication of your IP's reputation, but it doesn't represent the full picture across all mailbox providers.
When you observe a precipitous drop, say from 100 to 12 in a week, as was the case for one user sending millions of emails daily via dedicated IPs through an ESP like Braze (using Sendgrid IPs), it's crucial to understand the potential underlying causes. Even if Google Postmaster Tools shows minimal Delivery Errors or your ESP's portal reports no changes in standard metrics, a Sender Score decline indicates that your sending practices are being flagged by some part of the email ecosystem. This situation often points to problems that are not yet broadly visible but are actively impacting specific segments of your audience or certain receiving networks.
Understanding the nuances of Sender Score
Sender Score provides a quantitative measure of your sending reputation. It ranges from 0 to 100, with higher scores indicating better reputation. A good score typically means your emails are more likely to reach the inbox, while a low score can lead to emails being filtered to spam folders or rejected outright. Validity, the company behind Sender Score, compiles data from various sources, including participating internet service providers (ISPs) and their own network of spam traps.
Their mission is to help senders understand their reputation and improve email deliverability. However, it is essential to understand that not all mailbox providers share their internal reputation data with third-party services like Validity. For instance, large providers like Google often rely on their proprietary algorithms and data, which may not directly feed into public scores. This means your Sender Score could plummet while your deliverability to Google (and other providers not sharing data) remains seemingly unaffected, at least initially.
The paradox of a declining Sender Score with stable other metrics suggests that the issue might be confined to specific networks that Validity monitors or that the impact is not yet severe enough to cause widespread rejections or bounces across all your email sends. This situation highlights the importance of not relying on a single metric for your overall deliverability health. You should always be assessing multiple data points to get the most accurate view of your email program. If your Sender Score is low, it's considered a red flag for email deliverability.
Understanding Sender Score
Sender Score (by Validity) measures the reputation of your outbound IP address on a scale of 0-100. It's influenced by complaint rates, spam trap hits, email volume, and other factors observed across participating networks. A higher score suggests better deliverability, while a sharp drop indicates a significant reputational issue.
Why it might not align
Sender Score's data collection is limited to Validity's partners and proprietary networks. Large mailbox providers like Microsoft and Google use their own internal reputation systems, which might not reflect in public scores immediately. This can lead to a deceptive sense of stability in your ESP metrics while a problem is brewing elsewhere.
Hidden factors impacting your sender score
One of the most common reasons for a significant Sender Score drop, especially when other metrics seem stable, is hitting spam traps (also called honey pots). These are email addresses specifically designed to catch spammers. They often don't bounce, and since legitimate users don't engage with them, they won't show up as opens or clicks. However, sending to even a small number of these traps can severely damage your IP and domain reputation with anti-spam organizations and reputation services like Validity.
Another factor could be the proximity of your dedicated IPs to other IPs that are sending spam. Even with dedicated IPs, if your ESP's (Email Service Provider's) IP blocks contain other IPs engaged in questionable sending practices, it can indirectly affect your reputation. While you might have a dedicated IP, it's still part of a larger network. It is also possible that the recipients of your messages at ISPs that share complaint data with Validity are complaining, even if these complaints are not directly reflected in your ESP's high-level complaint metrics.
Furthermore, evolving spam filters and artificial intelligence (AI) at mailbox providers are constantly becoming more sophisticated. They can detect subtle signs of unwanted mail, such as low engagement over time, content characteristics, or inconsistent sending patterns, before these issues manifest as outright bounces or visible spam complaints. This can lead to your emails being silently filtered to the spam folder for a segment of your audience, impacting your overall sender score without immediately changing your reported open rates or bounce rates.
Apparent stability
Standard email metrics reported by your ESP typically include open rates, click-through rates, and bounce rates. When these metrics remain stable, it suggests that emails are being delivered and engaged with at a consistent level. However, these aggregated metrics might not capture the full nuance of deliverability, especially if issues are localized to specific mailboxes or networks.
Observed metrics
Open rates: Steady or slowly declining, not showing a sudden drop.
Bounce rates: No significant increase in hard or soft bounces.
Complaint rates: Reported complaints within the ESP portal remain low or unchanged.
Hidden decline
Beneath the surface of seemingly stable metrics, reputation problems can be brewing. These issues often stem from factors that are not directly measured by basic ESP reporting or are specific to certain receiving networks. A plummeting Sender Score is an early warning sign that should not be ignored.
Specific ISP complaints: Negative feedback to AOL or Comcast (who share data with Validity) may impact your score before broader trends.
Diagnosing the underlying issues
When your Sender Score drops but other metrics remain stable, it's crucial to investigate. Start by confirming if your IPs are truly dedicated and if their individual reputation is clean. You can use tools to verify the IP reputation on various blocklists (or blacklists). Even if not publicly listed, a poor score might indicate a private blocklisting or negative internal reputation at some providers. Check your email logs for any less common error codes or throttling messages that your ESP might not surface in high-level dashboards.
Next, dive deeper into your audience engagement and list hygiene. A low Sender Score often stems from sending to unengaged or low-quality lists. Are you regularly cleaning your lists? Are you re-engaging or suppressing inactive subscribers? Even if your overall bounce rate is low, the presence of spam traps in your list can silently erode your reputation. Re-evaluate your list acquisition methods to ensure you are only sending to genuinely opted-in users. Consider how your email engagement has changed over time.
Finally, review your email content and sending practices. Are there any recent changes in your content, subject lines, or sending volume/frequency? Sometimes, subtle changes in messaging can trigger spam filters or increase complaints. If you have identified the specific IP or domain that has dropped in Sender Score, this can guide your investigation. Addressing these underlying issues, even if they don't immediately show up in your primary metrics, is crucial for long-term email program health.
Why this matters for your email program
A dropping Sender Score, even with stable standard metrics, is a significant warning sign that your sender reputation is at risk. While your current deliverability may not show immediate adverse effects, neglecting this drop can lead to more severe problems down the line, including increased spam folder placement, email throttling, and outright rejections. Mailbox providers, including Apple Mail, are constantly updating their filtering mechanisms, and relying solely on easily accessible ESP metrics might not provide a complete picture.
The key is to adopt a proactive approach to email deliverability. This includes comprehensive blocklist (or blacklist) monitoring, thorough list hygiene practices, and ensuring your email authentication (SPF, DKIM, DMARC) is correctly configured and aligned. A strong email authentication setup, verifiable through DMARC monitoring, is fundamental to maintaining a good sending reputation. If Sender Score is inaccurate or low, it signals the need for immediate action, even if other metrics seem stable.
Ultimately, your Sender Score is a symptom, not the cause, of your email sending behavior. If it drops significantly, it's a strong indicator that your email program has underlying issues that need to be addressed before they escalate into widespread deliverability problems. Regularly monitoring a diverse set of reputation metrics, understanding their nuances, and acting on early warning signs are critical for ensuring your emails consistently reach the inbox.
Views from the trenches
Best practices
Maintain rigorous list hygiene by regularly removing inactive or unengaged subscribers to avoid hitting spam traps.
Segment your audience and tailor content to improve engagement, reducing complaints and increasing positive interactions.
Implement strong email authentication (SPF, DKIM, DMARC) to build trust with mailbox providers and prevent spoofing.
Common pitfalls
Ignoring a drop in Sender Score because other metrics appear stable, leading to more severe deliverability issues later.
Relying solely on ESP-provided metrics without checking external reputation tools or DMARC reports.
Sending inconsistent email volumes or making sudden, drastic changes to sending frequency.
Expert tips
Monitor granular logs for specific mailbox providers to identify hidden throttling or filtering not captured by aggregated metrics.
Use engagement metrics beyond opens and clicks, such as replies and marks as not spam, as strong positive reputation signals.
Engage in proactive IP and domain reputation monitoring to catch issues before they significantly impact your campaigns.
Expert view
Expert from Email Geeks says a Sender Score drop without corresponding inbox placement or bounce rate changes might indicate proximity to other spamming IPs or hitting Validity traps, not necessarily a deliverability problem.
2023-01-12 - Email Geeks
Marketer view
Marketer from Email Geeks says Validity's Sender Score only reflects traffic in specific partner networks, so a low score does not always mean widespread deliverability issues, especially for providers like Google.
2023-01-12 - Email Geeks
Proactive reputation management
Addressing a dropping Sender Score requires a holistic approach that goes beyond surface-level metrics. It necessitates a deep dive into your sending practices, audience quality, and the specific feedback signals from various parts of the email ecosystem. Prioritize maintaining a clean and engaged subscriber list, ensure all email authentication protocols are correctly implemented, and regularly monitor your IP and domain reputation across multiple platforms.
Remember that reputation is built over time and can be damaged quickly. Even seemingly minor issues, if left unaddressed, can compound and lead to significant deliverability challenges. By proactively managing your email program and responding to early warning signs like a Sender Score drop, you can safeguard your email deliverability and ensure your messages consistently reach their intended recipients.
Focus on the long-term health of your email program. Implementing robust practices for list acquisition, content relevance, and technical compliance will naturally lead to a strong sender reputation across all metrics, not just those that are immediately visible.
Google and 
Yahoo) evaluate incoming mail. Sender Score is a metric provided by Validity, based on data collected from their network of email receivers and spam traps. It provides an indication of your IP's reputation, but it doesn't represent the full picture across all mailbox providers.
Sendgrid IPs), it's crucial to understand the potential underlying causes. Even if Google Postmaster Tools shows minimal Delivery Errors or your ESP's portal reports no changes in standard metrics, a Sender Score decline indicates that your sending practices are being flagged by some part of the email ecosystem. This situation often points to problems that are not yet broadly visible but are actively impacting specific segments of your audience or certain receiving networks.
Microsoft and Google use their own internal reputation systems, which might not reflect in public scores immediately. This can lead to a deceptive sense of stability in your ESP metrics while a problem is brewing elsewhere.
AOL or 
Comcast (who share data with Validity) may impact your score before broader trends.
Apple Mail, are constantly updating their filtering mechanisms, and relying solely on easily accessible ESP metrics might not provide a complete picture.
