How Sender Scores Affect Email Deliverability

Silvio Bonomi
Jun 13
14 min read

Updated: Sep 6

What is a Sender Score?A sender score is like a credit score for your email domain. It tells email providers how trustworthy you are based on factors like spam complaints, bounce rates, and engagement. A higher score means better chances of landing in inboxes, while a low score can send your emails straight to spam.

Why It Matters

83% of email deliverability failures are due to poor sender reputation.
A low sender score can cut your sales pipeline by up to 40% if emails don’t reach prospects.
Even well-written emails can fail if the sender score is low.

Key Factors That Impact Sender Scores

Spam Complaints: Keep rates below 0.3%.
Bounce Rates: Aim for 2–5%.
Spam Traps: Avoid purchased or outdated lists.
List Hygiene: Regularly clean and validate your email list.
Engagement: Higher open and click rates improve your reputation.

How to Improve Your Sender Score

Clean Your Email List: Remove invalid addresses and inactive users.
Warm Up New Domains: Gradually increase email volume over weeks.
Authenticate Emails: Set up SPF, DKIM, and DMARC.
Focus on Engagement: Personalize emails and segment your audience.
Monitor Your Score: Use tools like Sender Score, Google Postmaster, and MXToolbox.

Bottom Line: A strong sender score ensures your emails reach inboxes, driving better engagement and boosting your B2B sales pipeline.

Why Your Sender Score is Your Email's Credit Score with Ashley DeLuca and GlockApps

What Makes Up Your Sender Score

Sender scores bring together several factors to evaluate the trustworthiness of your emails. By understanding these components, you can pinpoint what might be lowering your score and take steps to improve your email deliverability.

Main Factors That Affect Sender Scores

Sender scores are based on a rolling 30-day average, meaning your recent email activity has the most influence. Email providers rely on specific metrics to shape your reputation profile, and these metrics are what separate high scores from low ones.

One of the most harmful factors is spam complaints. Domains with sender scores of 90 or higher typically maintain spam complaint rates below 1%, while those scoring 10 or less face complaint rates as high as 7.4%. Even a complaint rate above 0.3% can hurt your deliverability. When recipients mark your emails as spam, it signals to providers that your content isn’t welcome.

Another critical metric is the unknown user rate, which reflects how well you manage your email lists. Top-performing domains keep this rate around 1%, but for poorly performing domains, it can climb to 7%. This happens when emails are sent to invalid addresses, often because of outdated contact lists or poor data hygiene.

Spam trap hits are another red flag. These occur when emails are sent to addresses designed to catch spammers. High-scoring domains average just 0.36% spam trap hits, while low-scoring domains deal with rates of about 7.53%. Spam traps often lurk in purchased lists or neglected databases.

Bounce rates also play a role. Ideally, they should stay between 2–5%. For example, in February 2025, Belkins experienced a spike in bounce rates to 19%, which hurt engagement. After using ZeroBounce to clean their lists, they reduced their bounce rate to 0.4%, restoring their sender reputation.

Other factors include proper email authentication (like SPF and DKIM), engagement metrics, consistent sending volumes, and whether your domain appears on industry blocklists.

Together, these factors determine whether your emails land in the inbox or the spam folder. Understanding these metrics helps clarify how sender and domain reputations contribute to your overall email performance.

Sender Score vs. Domain Reputation

Although people often confuse them, sender score and domain reputation are distinct.

Sender reputation combines your IP reputation and domain reputation. Your IP reputation focuses on the server sending your emails and is influenced by factors like sending patterns and spam complaints. If you’re on a shared IP, other senders’ actions can affect your reputation. Dedicated IPs offer more control but require steady email volume to maintain a positive reputation.

On the other hand, domain reputation is tied to your brand - the domain in your "from" address. It’s influenced by the quality of your email content and engagement metrics, such as open rates. Unlike IP reputation, domain reputation is portable and remains with your brand, regardless of the IP or email service provider you use.

The weight of these factors varies by email provider. For example, Gmail has increasingly prioritized domain reputation for authenticated emails, while others still balance domain and IP reputation.

This dual-system means you can’t overlook either aspect. A strong domain reputation won’t save you if your IP has been flagged for suspicious activity, and a clean IP won’t fully compensate if your domain has a history of sending unwanted emails. For B2B outreach, domain reputation is especially important over time, as it builds trust with both email providers and recipients. Meanwhile, IP reputation has a more immediate impact, particularly when scaling your email volume or launching new campaigns.

"Just because you have a great SenderScore doesn't mean you're going to have good delivery. Likewise, having a poor SenderScore doesn't mean your mail is destined to be undelivered." - Laura Atkins, Founder at Word to the Wise

How Low Sender Scores Hurt Email Deliverability

Low sender scores can seriously disrupt your email campaigns and harm your business relationships.

Spam Placement and Delivery Failures

A low sender score sends a warning signal to email providers, suggesting your messages might be unsafe or unwanted. This can trigger spam filters, redirecting your emails to junk folders instead of inboxes. In fact, nearly 20% of permission-based emails never make it to their intended inboxes because they’re flagged as spam or junk. When your reputation dips below certain thresholds, email service providers may go as far as blocking your domain or locking specific accounts.

Modern algorithms evaluate sender scores alongside other factors. For instance, 69% of recipients decide to mark emails as spam based solely on the subject line. But a low sender score puts your emails at a disadvantage before they even get opened. Worse yet, it creates a vicious cycle: a poor reputation leads to higher bounce rates, which further damages your score and makes it even harder for future emails to reach inboxes.

If your deliverability rate falls below 95%, your bounce rates will increase significantly. This decline in engagement signals to mailbox providers that your domain is unreliable, causing even high-quality emails to be flagged as spam. As a result, even your best-crafted email templates can lose their effectiveness when your sender score is compromised.

The consequences of these delivery failures are far-reaching, especially when it comes to revenue generation.

Impact on B2B Sales Pipelines

For B2B companies, a low sender score can derail entire sales pipelines. Poor inbox placement leads to low open rates, which stifles outreach efforts and halts the sales process. If your emails don’t reach decision-makers, your ability to generate leads and close deals is severely diminished.

The financial losses can be staggering. Imagine a sales team sending 2,000 prospecting emails daily with a 1% target conversion rate. If 40% of those emails land in spam, the team misses out on 8 qualified leads every single day. At an average deal size of $1,000, that’s $8,000 in lost revenue daily - or over $240,000 per month.

Beyond lost revenue, poor email deliverability stretches out sales cycles, reduces productivity, and cuts into ROI. It also damages your brand’s reputation by lowering domain trustworthiness, which can even lead to blacklisting. With nearly 45% of global email traffic categorized as spam, email providers are becoming increasingly strict about sender reputation.

Consumer behavior adds another layer of difficulty. According to DMA research, 49% of consumers won’t open marketing emails from senders they don’t recognize, and 50% will mark such emails as spam. If your sender score is already low, gaining trust with new prospects becomes an uphill battle.

"I strongly believe if you don't have a product to monitor and improve inbox placement, investment in enablement for your sales team and other technologies like ZoomInfo and Outreach can be wasted because your reps' messaging isn't being seen by even your most targeted personas", says Richard Mullins, Head of Global Business Development at Workvivo.

A low sender score doesn’t just hurt your ability to reach prospects - it also prevents you from building relationships, qualifying leads, and advancing deals. For B2B companies, which often rely on email sequences to nurture prospects through long sales cycles, this can be devastating. Even the most sophisticated tech stacks, from CRMs to sales enablement tools, lose their effectiveness if your emails aren’t getting delivered. The ripple effects of poor deliverability can undermine multiple facets of your sales and marketing operations.

How to Improve and Maintain High Sender Scores

Restoring a solid sender score isn’t an overnight fix - it requires steady effort and attention to detail. By focusing on list quality, consistent sending habits, and engaging content, you can rebuild your reputation and keep your B2B sales pipeline healthy.

Best Practices for List Hygiene and Validation

Your email list’s quality plays a big role in determining your sender score. On average, mailing lists lose about 22% of their accuracy each year, with 3% of customer data becoming outdated every month. That’s why regular maintenance is non-negotiable if you want to ensure successful email delivery.

Start by immediately removing hard bounces from your list. These invalid addresses signal poor list hygiene to email providers, which can harm your reputation. Keeping your list clean is a cornerstone of maintaining a good sender score.

Using a double opt-in process is another smart move. This ensures that only engaged subscribers are added to your list, while also protecting against bot abuse. Surprisingly, more than half of email senders skip this step. Nick Schafer, Sr. Manager of Deliverability & Compliance at Sinch Mailgun, underscores its importance:

"I would recommend that every sender use a double opt-in all the time. Not only does it ensure you only acquire subscribers who are more likely to engage, but it also helps prevent bots from abusing signup forms, which is a significant email security risk."

Real-time email verification is another must-have tool. By catching invalid addresses before they make it onto your list, you can cut bounce rates by up to 21%.

For subscribers who aren’t engaging, implement a sunset policy. Run re-engagement campaigns for those who haven’t opened your emails in 90–180 days. If they remain inactive, remove them from your list. Regularly clean your list at least twice a year, while monitoring bounce reports monthly. Segmenting your list based on engagement levels can further improve your results, especially since 38.7% of senders rarely or never conduct proper list hygiene.

Consistency in Sending Volume and Warming Up New Email Accounts

Consistency in your sending patterns is just as important as list quality. Email providers keep a close eye on your sending habits, and sudden spikes in volume can trigger spam filters. For example, sending 100 emails one day and 100,000 the next can raise red flags with ISPs.

When setting up new email accounts or domains, warming them up gradually is essential. This process typically takes about four weeks. Start small - send 50–100 emails per day, then increase the volume by 10–20% weekly. This gradual approach can boost open rates from 50% to 80% over time. Even after the initial warmup phase, it’s a good idea to maintain steady sending patterns.

For teams with multiple sales reps, coordinate sending schedules to avoid inconsistencies. Erratic sending from one person can negatively impact deliverability for everyone, especially when using shared domains or IP addresses. Set clear daily and weekly sending limits that align with your overall email strategy.

Before you start any warmup process, make sure your domain is authenticated with SPF, DKIM, and DMARC records. These technical steps verify your legitimacy and lay the groundwork for a strong sender reputation.

Engagement and Personalization for Better Results

Technical fixes only go so far - your content also needs to resonate with recipients. High engagement rates signal to email providers that your messages are welcome, which directly improves your sender score. Personalization is particularly effective, with studies showing it can increase revenue by up to 760% and boost open rates by 26%.

One simple but effective tactic is to send emails from an individual rather than a corporate address. For example, in March 2023, HubSpot tested this by comparing emails sent from "HubSpot" versus those sent from a marketing team member. The personal sender saw a click-through rate of 0.96%, compared to 0.73% for the corporate sender - resulting in 292 more clicks.

Segmenting your email lists can also make a big difference. Instead of blasting generic messages to your entire database, tailor your campaigns based on factors like industry, company size, job title, or past interactions. This approach not only drives engagement but also reduces the likelihood of spam complaints.

As Tracie Pang, Email Marketing Manager at Litmus, puts it:

"When personalization is done right, it's something subscribers are more likely to engage with. They're more likely to click on a product, browse your website, and make a purchase."

Make it easy for recipients to unsubscribe with a simple, one-click option. This helps protect your sender reputation by allowing uninterested subscribers to opt out without frustration.

Keep a close eye on your engagement metrics and adjust your strategy as needed. Low open rates, high bounce rates, or an uptick in spam complaints are clear signs that something needs to change. HubSpot’s research highlights email deliverability as a feedback loop - success depends on sending the right content to the right people at the right time.

Timing and frequency also matter. Test different send times and days to see when your audience is most responsive. Strike a balance between staying top of mind and avoiding email fatigue.

Monitoring and Managing Sender Scores

Keeping a close eye on your sender score is a must for maintaining strong inbox placement. With 83% of emails failing to reach their destination due to poor sender reputation, consistent monitoring can make or break your B2B outreach efforts.

Let’s explore some tools and strategies to help you stay on top of your sender scores.

Tools for Monitoring Sender Scores

Think of sender score monitoring tools as your email reputation’s health tracker. These tools provide real-time insights into how your emails are being received across different platforms.

Here’s a quick breakdown of some of the most effective tools:

Tool	Key Features	Best For
Sender Score	Reputation score (0–100) with a 30-day rolling average	Assessing overall email reputation
Google Postmaster Tools	Insights into Gmail-specific delivery and errors	High-volume Gmail senders
Microsoft SNDS	Reputation data for Outlook/Hotmail	Microsoft email users
MXToolbox	Blacklist monitoring and quick checks	Spotting reputation issues fast
Spamhaus Project	Tracks email threats and blacklists	Security-focused monitoring

Best Practices for Regular Monitoring

For most senders, checking your sender score weekly is enough, but if you’re sending high volumes of emails, daily checks are smarter. Keep an eye out for warning signs like declining open rates, increasing bounce rates, or a rise in spam complaints.

Set up automated alerts. Many monitoring tools can notify you when your score dips below a safe threshold or if you land on a blacklist. These alerts give you the chance to address issues before they escalate.

Testing email delivery across platforms like Gmail, Outlook, and Yahoo is also essential. Since only 58% of users check their spam folders daily compared to 95% who check their main inbox, ending up in spam is almost as bad as being blocked entirely.

Another key step is verifying your SPF, DKIM, and DMARC settings regularly. These authentication protocols ensure your emails are less likely to be flagged as spam.

Keeping detailed records of your monitoring results is equally important. For example, in June 2022, Litmus saw their inbox placement drop from 98–99% to below 90%. They traced the issue to Gmail and took action by segmenting their subscribers based on engagement, suppressing unresponsive contacts, and gradually increasing sending volume while monitoring engagement. This approach helped them recover their sender reputation.

How Artemis Leads Supports Deliverability

At Artemis Leads, we follow these best practices to ensure top-notch deliverability for our clients. Here’s how we do it:

Gradual Account Warm-Up: We carefully scale new accounts while monitoring engagement metrics to establish a strong sender reputation.
High-Quality Lists: Instead of relying on generic or outdated purchased lists, we build targeted prospect lists tailored to your ideal customer profile. This results in better engagement, fewer bounces, and a stronger reputation.
Personalized Outreach: Every message we send is tailored to the recipient’s specific business needs, reducing the likelihood of spam complaints.
Technical Setup: We handle the backend essentials like SPF, DKIM, and DMARC setup, sending domain configuration, and optimal sending patterns to maintain positive reputation signals.
Multichannel Approach: By combining email and LinkedIn outreach, we ensure consistent, professional messaging across platforms. This cross-platform presence reinforces trust and builds credibility with prospects.
Continuous Monitoring: We track deliverability metrics for all campaigns, making real-time adjustments as needed. This allows you to focus on closing deals while we handle the technical side.

Our approach ensures that your email outreach stays effective and your reputation remains strong, giving you the best chance to connect with your audience.

Conclusion: Sender Scores Drive B2B Email Success

Your sender score is more than just a metric - it’s the backbone of your B2B email strategy. With only 79.6% of legitimate emails making it to their intended recipients, maintaining a strong sender score is essential.

A high sender score improves deliverability, which directly impacts your ability to generate qualified leads. Deliverability rates below 95% can lead to a sharp increase in bounce rates, weakening your email campaigns. On the other hand, better deliverability strengthens your sales pipeline, ensuring your messages reach the right audience.

In B2B outreach, the stakes are even higher. Nearly half of recipients (49%) won’t open emails from unknown senders, and 50% are likely to mark such emails as spam. Businesses that prioritize their sender scores experience measurable gains in lead generation and overall pipeline performance.

Every email you send affects your sender reputation, so consistent monitoring and upkeep are critical. Implementing strong authentication protocols, maintaining clean email lists, and crafting engaging content help establish a solid foundation for future success. By routinely tracking and improving your sender score, you protect your email strategy and set the stage for long-term growth.

Consistency pays off. Email marketing can boost purchase likelihood by 25%. When your emails consistently land in inboxes, you increase your chances of connecting with potential customers and driving meaningful results.

Focus on your sender score today to build a more reliable and scalable sales pipeline.

FAQs

Why are my emails going to spam, and how can I check and improve my sender score?

If your emails are ending up in spam, it might be because of a low sender score. This score reflects your email reputation and plays a big role in whether your messages reach inboxes. To find out your sender score, you can use tools like online reputation checkers or spam testing services. These tools can pinpoint problems that might be hurting your email deliverability.

To boost your sender score and avoid the spam folder, start by keeping your email list clean. Remove inactive or unresponsive contacts regularly. Use double opt-in to confirm that recipients truly want to hear from you, and steer clear of buying email lists. Also, make sure you're using proper email authentication protocols like SPF, DKIM, and DMARC - these help establish trust with email providers. It's also a good idea to monitor metrics like bounce rates and spam complaints to stay on top of your sender reputation.

How can I lower email bounce rates and improve deliverability?

To reduce email bounce rates and ensure your messages actually land in inboxes, start by implementing a double opt-in process. This extra step confirms that new subscribers have provided valid email addresses and are genuinely interested in your content.

Next, keep your email list in good shape by regularly removing invalid or outdated addresses. Another critical step is authenticating your domain, which helps prevent your emails from being marked as spam.

Beyond technical fixes, focus on crafting relevant, engaging, and personalized content. This not only keeps your audience interested but also strengthens your sender reputation - something email providers take seriously when deciding whether to deliver your emails. Finally, make it a habit to track your email performance and tweak your approach as needed to stay on track for long-term success.

How does a sender score impact email deliverability and B2B sales, and what steps can prevent potential revenue loss?

A sender score is a key factor in determining whether your emails make it to the inbox or get flagged as spam. If your sender score is low, your emails are more likely to end up in spam folders, which can drastically reduce the effectiveness of your B2B outreach. This, in turn, can hurt your sales pipeline and revenue.

To avoid these setbacks, it’s critical to maintain a strong sender score. Here’s how you can do it:

Authenticate your emails using protocols like SPF, DKIM, and DMARC to establish trust with email providers.
Regularly clean your email lists to remove invalid or inactive addresses, ensuring you’re reaching real recipients.
Craft engaging and personalized email content that connects with your audience and keeps them interested.

For businesses like Artemis Leads, which specialize in email outreach to connect companies with decision-makers, keeping a high sender score is essential. It not only ensures better deliverability but also helps unlock the full potential of every sales opportunity.