How Sender Score Works
Sender Score, operated by Validity at senderscore.org, calculates a 0-100 score for any email-sending IP address based on a 30-day rolling window of signals drawn from a network of ISP partners and mailbox providers. Key inputs include spam complaint rate, unknown user rate (bounces to invalid addresses), spam trap hits, volume consistency, and engagement rates. Scores above 80 are considered good; 70-80 is neutral but watched; below 70 triggers increased filtering by participating inbox providers. The score is updated daily and reflects the trailing month of activity, meaning both improvement and degradation happen gradually.
Why Sender Score Matters for B2B Marketing
While Sender Score is IP-specific rather than domain-specific, it remains a useful diagnostic for B2B email operations, particularly for teams sending from dedicated IPs or private ESPs. A low Sender Score is often the first quantifiable indicator of list quality problems before a full deliverability crisis hits. Sales and marketing teams running outbound sequences through platforms like Outreach or Apollo need to monitor the IPs those platforms use, shared pool degradation is a common hidden cause of declining reply rates that teams mistakenly attribute to messaging or timing.
Sender Score: Best Practices & Strategic Application
To improve a low Sender Score: stop sending to unengaged contacts immediately, run your full list through email verification, remove all hard bounces and spam complainers, reduce send frequency until engagement signals improve, and ensure SPF and DKIM are properly configured. Volume consistency also matters, spiking from 500 to 50,000 emails in a single day will suppress a score even if list quality is clean. Build volume increases gradually over 2-4 weeks.
Agency Perspective: Sender Score in Practice
Sender Score is one data point in a multi-signal deliverability picture. We use it in conjunction with Google Postmaster Tools domain reputation, Microsoft SNDS data, and direct inbox placement tests (via GlockApps or Mail-Tester) to give clients a complete view. No single score tells the full story, but Sender Score degradation below 70 is always a signal to pause non-critical sends and investigate immediately.
