Why has my sender score dropped and what can I do about it?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 May 2025
Updated 16 Aug 2025
8 min read
Discovering that your sender score has dropped can be unsettling. It is a critical metric that influences whether your emails reach the inbox or end up in the spam folder. Just like a credit score for your financial health, your sender score reflects the health of your email sending practices and how mailbox providers (like Gmail, Outlook, and Yahoo) perceive your sending reputation.
A decline in this score often signals underlying issues that need immediate attention. It means that something in your email program or sending behavior has changed, leading to a less favorable view from major ISPs. Ignoring a falling sender score can result in significant deliverability problems, impacting your communication and business operations.
In this guide, I will explore the common reasons behind a drop in sender score and provide actionable strategies to help you diagnose the problem, recover your reputation, and prevent future dips. Understanding these factors is the first step towards ensuring your emails consistently land in the inbox.
Understanding your sender score and its impact
My sender score is a numerical value, typically ranging from 0 to 100, which indicates the trustworthiness of an IP address or domain as an email sender. Higher scores, usually above 80, signify a good reputation, while lower scores suggest potential issues. This score is calculated by various providers, like Sender Score by Validity, based on a multitude of factors related to your sending behavior.
It is not merely an arbitrary number, but a comprehensive assessment that heavily influences your email deliverability. Mailbox providers use this score, among other internal metrics, to decide whether to accept your emails, place them in the inbox, or filter them to the spam folder. A strong sender score makes it more likely that your messages will reach their intended recipients, while a low score can lead to widespread blockages or placement in junk folders.
While Sender Score is a valuable indicator, it is important to remember that it is just one piece of the puzzle. Each mailbox provider has its own proprietary algorithms for determining sender reputation. However, a significant drop on a publicly available metric like this often correlates with a broader decline in your overall email deliverability performance. Pay attention to it, but also look at other metrics.
More than just a number
Your sender score provides valuable insight into your email program's health, but it is not the only factor internet service providers (ISPs) consider. It serves as a strong signal, indicating potential underlying issues that might also be impacting your deliverability across various mailbox providers, even if not directly reflected in a single score.
Always combine Sender Score monitoring with other deliverability metrics like open rates, click-through rates, bounce rates, and spam complaint rates from your ESP and Google Postmaster Tools.
Common culprits behind a sender score drop
Several factors can cause your sender score to drop. Understanding these common culprits is crucial for diagnosing the issue and taking corrective action. Often, it is not a single problem but a combination of factors that contribute to a declining reputation.
One of the most impactful factors is a surge in spam complaints. When recipients mark your emails as spam, it sends a strong negative signal to mailbox providers. Even a small percentage of complaints can significantly harm your reputation. This often happens if your content is irrelevant, unexpected, or if recipients struggle to find an unsubscribe link.
High bounce rates, especially hard bounces (permanent delivery failures), are another major red flag. They indicate that you are sending to invalid or non-existent email addresses, which suggests poor list hygiene. Spam traps, which are email addresses used by ISPs and blocklist operators to identify spammers, also contribute to reputation damage. Sending to a spam trap indicates you are not properly managing your lists or acquiring addresses legitimately.
Factor
Impact on sender score
Spam complaints
High complaint rates significantly reduce trust.
Bounce rates
Hard bounces especially indicate poor list quality.
Spam traps
Hitting these signals very bad list acquisition practices.
Low engagement
Few opens or clicks, many deletes without opening.
Content issues
Spammy keywords or poorly formatted emails.
Volume inconsistency
Sudden spikes in sending volume can raise suspicion.
Poor content quality, including spammy keywords, suspicious links, or unusually large attachments, can also trigger filters and lead to a score reduction. Moreover, inconsistent sending volume, such as sudden, massive email blasts from an otherwise low-volume sender, can look like a compromised account to ISPs, negatively impacting your score.
Finally, being listed on an email blocklist (or blacklist) is a strong indicator of reputation issues. These lists track IP addresses and domains that have been associated with spamming activities. If your IP or domain gets listed, it can severely restrict your email delivery. You can check for blocklistings using tools like MultiRBL, but understanding how email blacklists work is even more crucial. Being on a shared IP address can also mean your score is affected by other senders sharing the same IP.
Strategies to recover and improve your score
Once you have identified the potential reasons for your sender score drop, it is time to implement a recovery plan. This often involves a multi-pronged approach focusing on cleaning up your sending practices and rebuilding trust with mailbox providers. The first step is to pause any non-essential sending and conduct a thorough audit of your email program.
One of the most effective actions you can take is to meticulously clean your email list. Remove all inactive subscribers, hard bounces, and any addresses that have not engaged with your emails in a long time. Regularly pruning your list helps avoid spam traps and ensures you are only sending to engaged recipients, which boosts your sender reputation. A good list hygiene strategy is foundational.
Ensure your email authentication protocols are correctly set up and aligned. This includes Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting & Conformance (DMARC). These records verify that your emails are legitimate and prevent spoofing, which significantly improves trust with ISPs. A properly configured DMARC policy, in particular, signals to mailbox providers that you are serious about email security and deliverability. You can learn more about these protocols in my simple guide to DMARC, SPF, and DKIM.
Focus on content quality and subscriber engagement. Send valuable, relevant emails that recipients want to open and click. Personalization, clear calls to action, and easy unsubscribe options all contribute to a positive user experience, reducing spam complaints and increasing engagement signals. Maintain a consistent sending volume if possible, avoiding sudden spikes that can raise red flags with ISPs.
Finally, continuous monitoring of your sender score and other deliverability metrics is key. Keep an eye on bounce rates, spam complaint rates, and open rates. If you are using a shared IP, understand that your reputation might be influenced by others, but your own sending practices are paramount. Address any new issues promptly to prevent a further drop and work on rebuilding your reputation over time. You can find more comprehensive troubleshooting steps in my article on troubleshooting a dropping email sender score.
Your action plan
Audit and pause: Temporarily halt non-essential sends and conduct a thorough review of your email practices.
Clean your lists: Remove inactive subscribers, hard bounces, and all suspicious email addresses.
Strengthen authentication: Implement and ensure proper SPF, DKIM, and DMARC configurations.
Improve content and engagement: Send valuable emails that encourage opens, clicks, and positive interactions.
Monitor continuously: Regularly check your sender score and other key deliverability metrics.
Views from the trenches
Best practices
Always prioritize sending to engaged subscribers to improve your overall sender reputation.
Implement a double opt-in process for all new subscribers to ensure list quality from the start.
Regularly monitor DMARC reports to identify authentication failures and potential issues.
Segment your audience and tailor content to improve engagement and reduce spam complaints.
Common pitfalls
Sending emails to purchased or rented lists, which often contain spam traps.
Ignoring high bounce rates, indicating a need for list cleaning and validation.
Neglecting to set up or properly configure SPF, DKIM, and DMARC records.
Sending inconsistent email volumes, especially sudden, large increases without warming up.
Expert tips
If your score drops on a shared IP, review your practices and ask your ESP for a better IP block.
Focus on actual deliverability metrics, not just sender score, to gauge your true inbox placement.
A score above 70 is often acceptable, with scores above 90 considered very good.
Sender score can be particularly useful for diagnosing problems with dedicated IP addresses.
Expert view
Expert from Email Geeks says that a Sender Score above 70 is reasonable, and above 90 is quite good, but acknowledges the challenges of shared IP addresses where one cannot fully control the sending environment.
2023-01-20 - Email Geeks
Marketer view
Marketer from Email Geeks suggests that focusing too much on the Sender Score alone might be a misdirection, especially if actual deliverability issues are not observed.
2023-02-15 - Email Geeks
Restoring and maintaining a healthy sender score
A drop in your sender score is a clear signal that your email sending practices need immediate attention. By understanding the factors that influence your score, such as spam complaints, bounce rates, and blocklistings (blacklists), you are better equipped to diagnose the root cause.
Implementing a proactive strategy that includes rigorous list hygiene, proper email authentication (SPF, DKIM, DMARC), and a focus on engaging content will not only help recover your score but also strengthen your overall email deliverability. Consistent monitoring and adaptation are key to maintaining a strong sender reputation and ensuring your messages reliably reach the inbox.
