What is the difference between sender score and email deliverability?

A sender score is a third-party metric, like Validity 's Sender Score, that gauges the reputation of an IP address. Email deliverability refers to the percentage of emails that successfully land in recipients' inboxes, avoiding spam folders or blocks. While a good sender score can indicate a healthy reputation, it's not the sole factor determining deliverability, as ISPs use their own complex internal metrics.

If sender score isn't everything, what factors are more important to ISPs?

Mailbox providers rely more on real-time, behavioral signals than aggregated sender scores. These signals include recipient engagement (opens, clicks), spam complaints, direct user feedback, and authentication records (SPF, DKIM, DMARC). A strong domain reputation, built on consistent positive user interaction, often holds more weight.

What is considered a good sender score?

A score of 95 or above is generally considered excellent, indicating strong sending practices. A score between 90-94 is good. If your score consistently drops below 90, it signals potential deliverability issues that need immediate attention.

Should I be concerned about every drop in my sender score?

A sudden, short-term drop might be a transient issue, possibly due to a concentrated reputation problem with a specific ISP. However, a persistent decline over several days or weeks suggests underlying problems like increased spam complaints, high bounce rates, or being listed on a major blocklist .

How relevant is sender score to email deliverability? - Sender reputation - Email deliverability - Knowledge base

The question of how relevant sender score is to email deliverability often arises, and it's a valid one. Years ago, many of us in the email deliverability space, myself included, didn't give a huge amount of credence to it. The general rule of thumb was, if your score was 95 or above, you were good, and anything below that signaled trouble for the mailbox providers that considered it.

However, the landscape of email deliverability is constantly evolving. What was a significant factor years ago might hold less weight today, or conversely, new metrics might have risen in prominence. It's crucial to understand the nuances of how sender score fits into the broader picture of email sender reputation and overall inbox placement.

While a sender score can still offer a directional indicator, its direct impact can sometimes be overstated, especially when compared to the complex, proprietary algorithms internet service providers (ISPs) use. These algorithms often prioritize real-time engagement and behavioral metrics over a single, aggregated score.

Understanding sender score

Sender score is typically a metric that assesses your IP address's reputation, providing a number between 0 and 100. A higher score is generally indicative of a better reputation. Think of it like a credit score for your email sending practices.

Mailbox providers often factor in a sender's sender reputation score to decide whether your emails land in the inbox or the spam folder. This reputation is built on various factors, including your sending history, complaint rates, bounce rates, and whether your IP or domain is listed on any email blacklists (or blocklists). While Sender Score provides a numerical representation, it's just one piece of the puzzle.

It's important to remember that most major ISPs and mailbox providers, such as

Gmail and

Outlook, rely on their own internal, dynamic reputation systems rather than external, publicly available scores. These systems process billions of emails daily and learn in real time from user engagement.

Sender score's impact on deliverability

While Sender Score provides a snapshot of your IP's health, its relevance can vary depending on the specific recipients and the anti-spam filters they use. It's often most insightful for identifying persistent issues.

For example, if your Sender Score consistently drops below 90 for more than a week, it's a strong signal that you likely have serious deliverability problems. This could be due to a significant increase in spam complaints, high bounce rates, or potentially being listed on a major blocklist (or blacklist). Conversely, a brief, one- or two-day dip that quickly recovers to 95+ might just indicate a small concentration of reputation issues at an overrepresented ISP or anti-spam filter in the Sender Score panel, rather than a widespread problem.

The correlation between a good Sender Score and high deliverability at top ISPs can sometimes be coincidental. Many ISPs have their own proprietary systems that factor in a multitude of signals, making a single external score less critical. For more on what contributes to this score, check out our guide on Sender Score data sources.

External scores

Focus: Provide a generalized view of IP reputation across various networks.
Utility: Good for initial diagnostics and trend monitoring over time.
Limitations: May not reflect specific ISP policies or real-time user engagement.

Beyond the sender score

To truly improve email deliverability, you need to look beyond a single metric. Mailbox providers calculate a sender's reputation score based on a multitude of real-time signals. These include how recipients interact with your emails.

Key factors that influence your deliverability (and indirectly, your sender score) include: high bounce rates, spam complaints, engagement (opens, clicks, replies, deletions without opening), and whether your emails pass email authentication checks (SPF, DKIM, DMARC). A strong domain reputation is often more critical than a high IP score alone.

We've also seen instances where specific ISPs, like

Comcast, have historically placed more emphasis on Sender Score-based volume thresholds. While this might have been a factor in a handful of cases, it's generally not the primary driver for most top mailbox providers today. If you're seeing a low score, it's worth understanding why your sender score is low.

Sender score

Calculated by Validity, it provides a general reputation index for your sending IP address. It aggregates data from various sources to give a numerical score.

Factors: Complaint rates, volume, unknown users, rejection rates, external blocklist (or blacklist) listings.
Use: A good starting point for reputation monitoring and diagnosing widespread issues.

ISP internal reputation

Each ISP (e.g., Gmail, Outlook, Yahoo) maintains its own proprietary, real-time reputation system based on direct interactions with your emails.

Factors: User engagement (opens, clicks), spam complaints, spam trap hits, authentication, domain health.
Use: Directly determines inbox placement. The most crucial measure of deliverability.

Prioritizing reputation management

For low-volume senders, or those just starting, external sender scores may not provide a complete or accurate picture. Building reputation for low-volume sending is a different ballgame than for high-volume senders. Our article on interpreting sender reputation scores effectively delves deeper into this.

Regardless of volume, your goal should be to maintain a positive sender reputation by focusing on consistent sending practices, good list hygiene, and delivering valuable content to engaged subscribers. This holistic approach will naturally lead to better deliverability and positively influence all reputation metrics, including your sender score.

Ultimately, a good sender score of 95+ is desirable, but it's more a symptom of good sending practices than the sole cause of good deliverability. Focus on the fundamentals, and the scores will often follow. If you're experiencing a sudden drop, we have a guide on how to address a dropping sender score.

Score Range	Implication	Action Required
95-100	Excellent reputation. Emails are generally trusted by mailbox providers.	Maintain current sending practices, monitor for any changes.
90-94	Good to fair reputation. Some minor issues or inconsistencies might be present.	Review engagement metrics, ensure list hygiene. Consider deliverability best practices.
70-89	Problematic reputation. Emails may experience deferrals or land in spam folders.	Investigate complaint rates, monitor for blacklist listings, re-engage or remove unengaged subscribers.
0-69	Poor reputation. High likelihood of emails being blocked or sent to spam.	Urgent action required. Review entire sending program, clean lists aggressively, implement email authentication.

Views from the trenches

Best practices

Actively monitor engagement rates, open rates, and click-through rates.

Implement a robust list hygiene strategy to regularly remove invalid or inactive email addresses.

Segment your email lists to send targeted content that resonates with your audience.

Ensure all technical email authentications (SPF, DKIM, DMARC) are correctly configured.

Common pitfalls

Over-reliance on a single reputation score without considering broader deliverability metrics.

Ignoring high bounce rates or spam complaints, leading to long-term reputation damage.

Sending emails to purchased or old lists, increasing the risk of hitting spam traps.

Failing to warm up new sending IPs or domains gradually before sending large volumes.

Expert tips

Use Google Postmaster Tools for invaluable insights into your domain's reputation with Google.

Subscribe to feedback loops (FBLs) from major ISPs to receive real-time spam complaint data.

Diversify your sending IPs or domains if you send different types of email (transactional, marketing).

Regularly test your email deliverability across various mailbox providers to identify issues early.

Marketer view

Marketer from Email Geeks says Sender Score relevance depends on recipient and sensor data, but 95+ is generally a good indicator.

Feb 28, 2023 - Email Geeks

Marketer view

Marketer from Email Geeks says Sender Score has been most relevant for Comcast recipients due to their volume thresholds, though this was infrequent.

Feb 28, 2023 - Email Geeks

The full picture of deliverability

While a good sender score can offer reassurance and serve as a useful diagnostic tool, it's not the ultimate determinant of your email deliverability. The email ecosystem is far more complex, with ISPs focusing heavily on direct user engagement and a myriad of other behavioral signals.

Ultimately, what matters most is consistent, respectful sending practices that prioritize the recipient. By focusing on maintaining a healthy sender reputation through proper list management, content relevance, and technical adherence, you'll naturally improve your inbox placement rates, regardless of where your external sender score stands at any given moment.