TL;DR
A sender score is a 0–100 reputation metric assigned to sending IPs and domains by Validity (formerly Return Path) that inbox providers use to determine inbox vs. spam routing. Scores above 80 indicate strong sending health; below 70 correlates with measurably worse inbox placement; below 50 means most email is going to spam or being rejected (Validity Sender Score Methodology 2024).
What is a sender score?
A sender score is a numerical reputation score (0–100) calculated by Validity (the company that acquired Return Path's Sender Score service) for sending IP addresses and domains — based on complaint rates, bounce rates, spam trap hits, volume consistency, and engagement patterns. Inbox providers and spam filters use sender scores alongside their own internal reputation data to decide whether incoming email routes to inbox, spam, or is rejected.
The Sender Score is one of several reputation signals (Google has its own, Microsoft has its own) but it's the most widely cited cross-ISP reputation indicator available for free lookup. A score above 80 is considered healthy. A score between 70–80 is borderline. Below 70, expect increasingly unreliable inbox placement. Below 50, most email is routing to spam.
For sales teams running cold outreach, sender score is a lagging indicator — it reflects damage that has already happened. By the time a score drops from 85 to 65, the sending domain has already accumulated significant negative signals. This is why proactive monitoring (checking weekly, not after a failed campaign) is the only reliable way to use sender score as a management tool.
What affects sender score
Validity calculates Sender Score from a rolling 30-day window of sending behavior. The inputs most heavily weighted:
- Spam complaint rate — recipient reports of spam are the highest-weight negative signal. Each complaint erodes score immediately. Target: below 0.1% of sends.
- Unknown user (invalid address) rate — emails sent to addresses that don't exist signal list quality problems. Target: below 1–2% of sends.
- Spam trap hits — sending to addresses maintained by anti-spam organizations to catch bulk senders. Even one or two trap hits per week measurably damages score.
- Volume consistency — sudden spikes from new domains or unusually large campaigns. Consistent, predictable send volume is positive; anomalous volume changes are negative.
- Positive engagement — opens, replies, forwards. These signals counterbalance negative ones. A sender with 8% reply rate can sustain a higher send volume than one with 0.5% reply rate.
- Blacklist status — whether the sending IP or domain appears on any major blocklists (Spamhaus, Barracuda, Cloudmark). Blacklist appearance drops score sharply.
Common sender score mistakes
1. Treating sender score as a periodic check rather than a weekly monitor. A score of 82 this week and 64 next week means something went very wrong in 7 days. Weekly monitoring catches degradation before it becomes a crisis.
2. Confusing IP reputation and domain reputation. Sender Score tracks the sending IP (the server your email goes through) as well as the domain. If you use a shared IP (via a sending platform like Mailgun or SendGrid), your score is partially influenced by other senders on the same IP. Moving to a dedicated IP isolates your reputation.
3. Not correlating sender score with campaign performance. A drop in sender score should immediately prompt a review of which campaign was running that week — to identify whether a specific list, sequence, or message type caused the spike in negative signals.
4. Ignoring the score until it's below 50. Recovery from a score below 50 takes 8–12 weeks minimum. Catching degradation at 70–75 and correcting it is a 2–4 week fix.
How to check and improve sender score
Check sender score at senderscore.org by entering your sending IP or domain. For cold outbound teams, check both the IP and the domain — and check weekly, not monthly. A dedicated sending IP (available from providers like Mailgun, SparkPost, SendGrid) gives you full control over IP reputation rather than sharing it with other customers on a shared pool.
To improve sender score: reduce bounce rate below 2% (verify email addresses before sending), reduce spam complaints below 0.1% (improve targeting and unsubscribe process), stop sending to any lists with spam trap risk (purchased lists), and maintain consistent send volume without spikes. Score improvement is gradual — 4–8 weeks of clean sending for every 10-point recovery.
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Frequently asked questions
What is a sender score?
A 0–100 numerical reputation score calculated by Validity for sending IP addresses and domains, based on complaint rates, bounce rates, spam trap hits, and sending consistency. Used by inbox providers as one factor in spam filtering decisions. Check at senderscore.org. Above 80 is healthy; below 70 is borderline; below 50 means most email is routing to spam.
What is a good sender score for cold email?
80 or above is the target for cold outbound senders. Scores between 70–80 will produce inconsistent inbox placement — some ISPs will route to inbox, others to spam. Below 70, invest in a deliverability audit before continuing cold sends. A score below 50 means the sending domain or IP needs to be rested or replaced before cold outreach can be effective.
How often should you check sender score?
Weekly for active cold outbound sending domains. Sender Score updates daily, but checking weekly is sufficient to catch emerging problems before they become severe. Check immediately after any campaign that produced unusually high bounce rates or spam complaints, or after any volume spike. Set a calendar reminder — weekly checks take under 5 minutes.
What's the difference between sender score and Google Postmaster reputation?
Sender Score (Validity) is a third-party cross-ISP score based on data from a network of ISPs and spam filter providers. Google Postmaster Tools shows Google's own domain reputation specifically for sends to Gmail. Both matter — Google Postmaster gives the most accurate signal for Gmail inbox placement; Sender Score gives a cross-ISP view. Use both for complete visibility.
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