Email deliverability relies heavily on your sending reputation, a key metric that internet service providers (ISPs) use to determine whether your emails reach the inbox or are filtered into the spam folder. One of the most widely recognized reputation metrics is SenderScore, a numerical rating from 0 to 100 assigned to an IP address. While most email marketers are familiar with checking their score via the SenderScore website, there's a lesser-known but powerful method to retrieve this data: a direct DNS lookup.
Understanding how to get your SenderScore through a DNS lookup can be incredibly useful for those who need to automate reputation monitoring or integrate it into their internal systems. This approach bypasses the need for manual website checks, offering a more efficient way to keep tabs on your email sending health.
This method is particularly valuable for high-volume senders or email service providers managing multiple IP addresses. It allows for quick, programmatic checks that can be integrated into custom dashboards or alert systems, providing real-time insights into your reputation without constant manual intervention.
What is SenderScore?
SenderScore is a proprietary reputation service developed by Validity (formerly Return Path). It aggregates data from a network of email receivers and anti-spam filters to assign a score to an IP address, reflecting its trustworthiness over a rolling 30-day period. A higher score, ideally above 80, indicates good sending practices and a strong likelihood of inbox placement, while a lower score can lead to emails landing in spam or being rejected outright.
This score is influenced by numerous factors, including spam complaints, bounce rates, subscriber engagement, and whether the IP address is listed on any email blocklists (or blacklists). It provides a snapshot of your IP's overall health and is frequently used by ISPs like Microsoft and Yahoo to make filtering decisions.
Monitoring your SenderScore is a proactive measure in maintaining good deliverability. A sudden drop can indicate an underlying issue with your email program, such as increased spam complaints, a compromised IP, or hitting a spam trap. Regular checks allow you to identify and address these problems before they significantly impact your inbox placement rates, highlighting how relevant SenderScore is to deliverability.
Performing the DNS lookup
While senderscore.org offers a user-friendly interface to check a single IP or domain, this can be cumbersome for large-scale operations. The DNS lookup method provides a direct, machine-readable way to query the SenderScore reputation database. This is achieved by forming a specific DNS query for your IP address, reversed, under a special SenderScore domain.
To perform a DNS lookup, you need to reverse the octets of your IP address and append them to .score.senderscore.com. For example, if your sending IP is 192.0.2.100, the query would be 100.2.0.192.score.senderscore.com. You then perform a standard DNS A record lookup on this constructed hostname.
Example DNS lookup using digbash
dig A 100.2.0.192.score.senderscore.com
The result you're looking for is an IP address, typically in the format of 127.0.X.Y. The last octet, Y, will be your SenderScore. For instance, if the lookup returns 127.0.4.99, your SenderScore is 99.
Interpreting the results
Interpreting the raw DNS lookup result is straightforward once you understand the format. The final octet of the returned 127.0.X.Y IP address directly corresponds to your SenderScore. A score of 99 indicates excellent reputation, while a score of 10 or lower suggests significant deliverability issues that need immediate attention.
It's important to note that the other octets (127.0.X) generally don't convey specific score-related information in this context, unlike some other DNS-based blocklists (or DNSBLs) that might use them to signify various listing reasons. For SenderScore, the last octet is your primary focus.
While this DNS lookup provides a numeric score, it doesn't offer the detailed breakdown or contextual information that you might find on the SenderScore website. For deeper insights into why your score is what it is, or if you suspect inaccurate data, you'll still need to consult the official website or other reputation tools.
Advantages and limitations
The primary advantage of using a DNS lookup for SenderScore is the ability to automate checks. This is invaluable for maintaining continuous oversight of your email deliverability health. Instead of manually entering IP addresses into a web form, scripts can perform these lookups at regular intervals, flagging any significant drops in score for immediate attention. This automation can be particularly useful for identifying issues quickly and preventing extended periods of poor deliverability.
However, this method does have its limitations. The primary one is that it provides only the score itself, without any of the detailed reporting that the SenderScore.org website offers. For example, it won't tell you if you're on a specific blacklist (or blocklist), or offer insights into spam trap hits or complaint rates, which are critical for troubleshooting a dropping score.
Another consideration is the potential for excessive queries. While convenient for automation, performing too many DNS lookups in a short period could potentially lead to your querying IP being temporarily blocklisted by SenderScore's DNS system to prevent abuse. It's essential to implement sensible rate limiting if you're building an automated solution.
Also, it's worth noting that Validity (the company behind SenderScore) has indicated plans to deprecate the public DNS lookup for SenderScore. While it remains functional for now, relying solely on this method for long-term monitoring might not be sustainable. It's always best to combine programmatic checks with official tools and APIs where available for a comprehensive view of your email deliverability.
Views from the trenches
Best practices
Implement automated scripts to perform daily or hourly SenderScore DNS lookups for all your sending IPs.
Log the historical SenderScore data alongside other email metrics to identify trends and anomalies.
Use the DNS lookup as a quick health check indicator, then refer to the SenderScore website for detailed reports.
Integrate SenderScore data into your existing monitoring dashboards to provide a unified view of your sending reputation.
Common pitfalls
Relying solely on the DNS lookup for all SenderScore insights, missing crucial details provided on the website.
Performing excessive DNS queries in a short timeframe, which can lead to your querying IP being temporarily blocked.
Misinterpreting the DNS response if it's not in the expected 127.0.X.Y format.
Not having a fallback monitoring strategy once the public DNS lookup method is officially deprecated.
Expert tips
For large volumes of IPs, consider staggering your DNS lookups to avoid rate limiting issues.
Combine DNS lookup data with other reputation signals, like Google Postmaster Tools, for a holistic view.
Set up alerts for significant drops in SenderScore (e.g., a drop of 10 points or more) to trigger immediate investigation.
Educate your team on what the SenderScore means and how to act on the information it provides.
Marketer view
Marketer from Email Geeks says they daily track their SenderScore data by IP, manually looking up IPs and copying them into a Google Sheet, which is helpful for seeing spam trap counts.
2021-03-25 - Email Geeks
Expert view
Expert from Email Geeks says it's unnecessary to screen scrape SenderScore data daily when a DNS lookup against your IPs can provide the score directly.
2021-03-25 - Email Geeks
Final thoughts on programmatic reputation monitoring
While the official SenderScore website provides a comprehensive dashboard, the DNS lookup method offers a quick, programmatic way to retrieve your IP's reputation score. This can be a powerful tool for automation, allowing you to integrate SenderScore monitoring directly into your existing systems and workflows.
By understanding and utilizing this DNS-based approach, you can enhance your ability to proactively monitor your email sending health, quickly identify potential reputation issues, and maintain optimal deliverability. Remember to use it judiciously and complement it with more detailed reputation analysis from official sources for a complete picture.
Staying vigilant about your SenderScore, whether through direct lookups or detailed reports, is a cornerstone of successful email marketing. It ensures that your messages reach their intended recipients, fostering stronger engagement and better campaign performance.
Microsoft and 
Yahoo to make filtering decisions.
