Sender Score explained: what it is, how to improve it
Validity's Sender Score is the most-quoted reputation metric in cold email and the most misunderstood. Here's what it measures, what it doesn't, and where it sits in the modern reputation stack.
What Sender Score actually is
Sender Score is a 0–100 rating issued by Validity (formerly Return Path) for sending IP addresses. It rolls up data from a network of receiving servers, spam traps, complaint feedback loops, and engagement signals across roughly 60 million mailboxes. The score is rolling — it represents the last 30 days of behavior from your IP.
Free at senderscore.org, you can look up any IP. You can't look up a domain — Sender Score is an IP-based metric, which is the first thing most cold senders get wrong.
Why Sender Score doesn't fully apply to Gmail
Gmail does not report into the Sender Score network. Neither does Microsoft 365. The two providers that handle ~80% of business email traffic operate their own reputation systems — Google Postmaster Tools and Microsoft SNDS — and neither feeds Validity.
So a Sender Score of 98 doesn't mean Gmail trusts you. It means the receivers in Validity's network trust you — primarily ISPs, smaller providers, and corporate gateways. Useful, but incomplete.
Sender Score is a credit score from one bureau. Postmaster Tools is a credit score from a different bureau. They overlap but they aren't the same number.
What it measures (and weights)
| Signal | Approximate weight | What it captures |
|---|---|---|
| Complaint rate | ~30% | This-is-spam clicks via feedback loops |
| Spam trap hits | ~25% | Sending to dormant or pristine traps |
| Unknown user rate | ~15% | Hard bounces from invalid addresses |
| Blocklist presence | ~15% | Spamhaus, SURBL, internal blocklists |
| Engagement | ~10% | Opens, clicks, replies where measurable |
| Authentication | ~5% | SPF/DKIM alignment, DMARC posture |
Validity doesn't publish exact weights, but the rank-order is well understood. Complaints and spam traps dominate. If you fix nothing else, fix those two.
Score bands and what they mean
- 90–100 Excellent. Mailbox providers in Validity's network deliver to inbox by default.
- 80–89 Good. Most messages reach inbox; some borderline content lands in promotions.
- 70–79 Mediocre. Aggressive filtering on new recipients. Engagement matters more than content.
- 50–69 Poor. Many providers throttle or send to spam by default.
- < 50 Bad. Likely on blocklists. Stop sending and rehabilitate.
of IPs scoring 90+ achieve inbox placement across the Validity panel. Below 70, that drops to roughly 30%. The score isn't arbitrary — it maps to behavior receivers care about.
How to look up your Sender Score
- Find the sending IP. For Gmail Workspace, it rotates within Google's pool — Sender Score effectively scores Google, not you.
- For SMTP relays (SendGrid, Mailgun, Amazon SES), find the dedicated IP from your provider dashboard.
- Visit
senderscore.organd create a free account. - Enter the IP. The score updates daily, but reputation moves in 7-day windows.
If you're sending cold email from Gmail or Outlook directly (the standard modern approach), Sender Score is largely irrelevant — the IPs aren't yours. Focus on domain reputation instead.
Moving the score up
1. Stop hitting spam traps
Pristine traps are addresses that have never opted in to anything. If you hit one, the only way you got that address is via scraping — and Validity knows. Recycled traps are dormant addresses repurposed as traps. The fix is the same: rigorous verification and never email anyone older than 12 months of engagement.
2. Crush complaint rate
Complaint rate above 0.1% is a major drag. Reduce it by: better targeting (don't email people who can't buy from you), tighter unsubscribe UX (one click, no friction), and avoiding the patterns that trigger "mark as spam" reflexes — fake urgency, hidden senders, unsolicited invoices.
3. Tighten authentication
Sender Score weights authentication lightly, but Validity penalizes failures heavily — a SPF/DKIM mismatch can drop you 5–10 points overnight. Get all three records right; see our authentication guide.
4. Drive real engagement
Replies are the strongest engagement signal. Opens are noisy post-MPP. If you're running cold campaigns, layer template-based warmup to keep reply ratios healthy on the actual template you're sending.
5. Stay off blocklists
Spamhaus listing tanks the score immediately. Check weekly withmultirbl.valli.orgor your sending tool's monitor. If listed, file a delisting request, fix the root cause, and pause sending for at least 72 hours.
Sender Score for Workspace and Microsoft 365 senders
Most cold email runs through Google Workspace or Microsoft 365 mailboxes, which means the sending IP is shared across thousands of tenants. Your Sender Score is effectively Google's or Microsoft's — and theirs is fine. For these setups, the relevant reputation metrics are:
- Domain reputation in Google Postmaster Tools (per-domain).
- SNDS data from Microsoft for the sending IP block.
- Inbox placement from a seed-test panel — the only true measurement.
Sender Score still matters when you're emailing recipients on smaller providers (university domains, hosted Exchange, regional ISPs). It just isn't the whole picture anymore.
The full reputation stack
Modern cold email reputation is four layers: IP reputation (Sender Score for relays, ignored for Workspace), domain reputation (Postmaster Tools), content reputation (mailbox-provider fingerprinting), and engagement reputation (replies, forwards, stars). Each requires different monitoring and different fixes.
For a complete view of how these interact, see the 2026 email warmup guide and the deliverability checklist.
Keep reading
All posts ↗- Soft Bounce vs Hard Bounce: What Actually DiffersSoft bounce vs hard bounce — SMTP 4xx vs 5xx, why one is temporary and one is permanent, retry policy, and how each affects sender reputation.
- Domain Reputation: How Mailbox Providers Score Your DomainDomain reputation — what mailbox providers measure, where to check your score (Postmaster, SNDS, Sender Score), and how to repair a damaged sending domain.
- Cold Email vs Marketing Email: The Real DifferencesCold email vs marketing email — different intent, different infrastructure, different rules, and why mixing them on one domain kills deliverability.
- Email Warmup in 2026: The Complete GuideThe 2026 email warmup guide — what warmup actually does, how mailbox providers measure it, why sender-only warmup falls short, and the playbook that works now.