TL;DR
Sender Score is a 0 to 100 reputation grade assigned to every sending IP address by Validity. It scores the IP against a rolling 30-day window of behavioral signals: complaint rate, bounce rate, spam trap hits, blacklist appearances, unknown-user rejections, and volume volatility. Mailbox providers consume the score as a trust signal when deciding to inbox, throttle, or reject your mail.
What Sender Score actually measures
Sender Score is the closest thing email has to a universal credit score. Validity aggregates data from a network of mailbox providers, spam filters, and feedback loops that cover roughly 80 percent of global B2B inbox volume. Every IP that sends commercial mail gets graded, whether the operator wants the grade or not.
The grade matters because mailbox providers do not have time to evaluate every sender from scratch on every connection. They rely on reputation signals to make routing decisions in milliseconds. A high score buys the benefit of the doubt. A low score means your mail gets second-guessed at every hop, and second-guessed mail rarely ends up in the primary inbox.
For sales teams running outbound, a drop from 95 to 75 routinely cuts cold-email reply rates in half because mail that used to land in Promotions now lands in Spam. Reps blame the copy. The real problem is the IP. Sender Score is also operator-facing — anyone can look up any IP at senderscore.org, which makes it the standard reference point when a vendor or compliance team asks how clean your sending is.
How Validity calculates the score
The model is a weighted average of six behavioral signals collected over a rolling 30-day window.
| Signal | What it measures | Weight |
|---|---|---|
| Complaint rate | Recipients who hit the "report spam" button | High |
| Unknown user rate | Hard bounces for invalid addresses | High |
| Spam trap hits | Mail to pristine or recycled traps | High |
| Blacklist appearances | Listings on Spamhaus, SURBL, Barracuda | Medium |
| Filtering rate | Mail filtered to junk vs delivered to inbox | Medium |
| Volume volatility | Sudden spikes or drops in send volume | Low |
The model favors stability. Validity refreshes the public score roughly every 24 hours but the underlying window is 30 days. That delay prevents a single bad campaign from destroying the grade and prevents a single clean week from masking a chronic problem.
Score brackets: bad, OK, great
| Bracket | Range | Inbox behavior | Action |
|---|---|---|---|
| Bad | 0 to 70 | Most mail filtered to spam or rejected. Microsoft and corporate filters block at the gateway. | Pause sending. Begin a 30 to 60 day repair protocol. |
| OK | 70 to 90 | Mixed placement. Gmail mostly inboxes, Yahoo selectively filters, Microsoft throttles. | Audit list quality. Tighten suppression. Watch trends weekly. |
| Great | 90 to 100 | Primary inbox at all major providers. Throttling rare. Corporate filters trust the IP. | Maintain the discipline that got you here. Monitor for early-warning dips. |
Treat 90 as the real operational floor for any outbound sales program. The brackets also behave asymmetrically. Moving from 70 to 80 takes weeks of clean sending. Moving from 95 to 75 can happen in 48 hours if a single campaign generates a spike in complaints or hits a recycled spam trap network. This asymmetry is why operators monitor the score daily, not monthly.
What hurts your Sender Score
Five categories of behavior account for nearly every Sender Score collapse.
Complaints
A complaint is registered when a recipient marks your mail as spam. Google publishes 0.3 percent as the upper bound in its Sender Guidelines. The most common cause in cold outbound is targeting the wrong persona or sending to a list that did not opt in.
Spam traps
Pristine traps are addresses that have never opted in anywhere. Recycled traps are abandoned mailboxes providers repurpose after long dormancy. A single pristine trap hit can drop your score by 10 to 20 points and land you on Spamhaus SBL.
Bounces
Hard bounces for invalid addresses count as unknown-user rejections. Sustained bounce rates above 2 percent directly lower the Sender Score. Run every new address through a verifier such as ZeroBounce or NeverBounce before it enters the sending list.
Blacklist appearances
Validity treats appearances on major blocklists as a negative input. The Spamhaus SBL, XBL, and PBL are the most consequential. A listing on Spamhaus SBL routinely drops Sender Score by 20 to 40 points within 24 hours.
Volume volatility
Sudden volume changes are themselves a risk signal. An IP that sends 1,000 emails a day for 30 days and then sends 50,000 on day 31 will see its score dip even if all other metrics stay clean. Ramp volume in steady increments of no more than 30 to 50 percent week over week.
How to check your score at senderscore.org
Checking takes two minutes and costs nothing. The lookup is public and requires no account creation for a single IP check.
Identify your sending IP address. Pull a recent sent message, view the source, and find the topmost Received: from line that lists an IPv4 address.
Go to senderscore.org and enter the IP in the lookup field. The lookup returns the current score, the 30-day trend, the volume tier, and any major blacklist appearances.
Sign up for a free Validity account to track multiple IPs over time and set alert thresholds.
Cross-reference with Google Postmaster Tools and Microsoft SNDS to see how the largest two providers grade your domain and IP separately.
Log the score weekly. A static snapshot is not enough. Trend lines reveal problems weeks before they cause real damage.
How to repair a damaged Sender Score
There is no shortcut. The rolling 30-day window means corrective behavior takes weeks to register.
Stop the bleeding
Pause every campaign touching an unengaged segment. Stop sending to anyone who has not opened or replied in the last 60 days. Volume drops by 60 to 80 percent in the first 24 hours of a serious repair.
Audit the inputs
Pull complaint rate, bounce rate, and any blacklist listings from the last 30 days. Identify the specific campaign, segment, or list source that triggered the drop.
Suppress aggressively
Add every hard bounce, every complaint, every unengaged-90-day address to a permanent suppression list. Remove every scraped or purchased list from circulation.
Warm back up
Send low volumes to your most engaged segment for 7 to 14 days. Increase volume by 30 percent per week. Keep complaint rate below 0.1 percent and bounce rate below 1 percent throughout.
Monitor daily and delist from blocklists
Check Sender Score, Google Postmaster, and Microsoft SNDS every morning. Request delisting from any blocklist after fixing the underlying behavior.
Recovery to a score of 90 plus typically takes 30 to 45 days of disciplined sending. Operators who try to shortcut the protocol almost always re-damage the IP and end up taking 90 days instead of 60.
Sender Score vs Google Postmaster vs Microsoft SNDS
Use Sender Score as the ecosystem-wide early warning system. Use Google Postmaster as the diagnostic when Gmail placement drops. Use Microsoft SNDS when Outlook or Office 365 placement drops.
| Dimension | Sender Score | Google Postmaster | Microsoft SNDS |
|---|---|---|---|
| Grades | IP (0–100) | Domain (primarily) | IP (Green/Yellow/Red) |
| Coverage | Cross-provider, ~80% of inbox traffic | Gmail only | Outlook, Hotmail, Live, Office 365 |
| Access | Free single lookup at senderscore.org | Free with domain verification | Free with account approval |
| Strength | Cross-ecosystem trust signal | Gmail placement detail | Microsoft placement and complaint rate |
Common mistakes that tank reputation
Behaviors that protect the score
- + Verify every new address before send
- + Suppress unengaged contacts after 60 days
- + Ramp volume by 30 percent per week, not 300 percent
- + Maintain SPF, DKIM, and DMARC alignment
- + Monitor Sender Score, Postmaster, and SNDS daily
Behaviors that destroy the score
- x Sending to scraped or purchased lists
- x Reactivating contacts cold after 12 months of silence
- x Launching a campaign at full volume on a new IP
- x Ignoring hard bounces and complaint feedback loops
- x Treating Sender Score as a monthly check rather than daily
How Gangly fits
Gangly is a sales workflow system, not an email service provider. What Gangly does is keep the inputs to the Sender Score clean by enforcing the workflow discipline that protects reputation. Inside Gangly, every outbound contact is sourced from a verified signal, not a scraped list. That single workflow change keeps complaint rates near zero because the recipient is genuinely relevant, not randomly targeted.
Suppression is automatic. Any hard bounce, any complaint, any 60-day unengaged address is suppressed without a rep having to remember. Volume is governed by the workflow. Reps cannot launch a 5,000 send burst on a fresh IP because the sequencer enforces a daily cap and a weekly ramp that matches the warmup protocol every major mailbox provider recommends.
See it in the product
Sender Score is a behavior mirror. Gangly keeps the inputs clean.
Signal-sourced contacts, automatic suppression, governed volume ramps — the workflow protects the reputation so you do not have to think about it.
Frequently asked questions
What is a good Sender Score in 2026?
A Sender Score above 90 is considered great and signals to receivers that your IP is a trusted sender. Scores between 70 and 90 are acceptable but expose you to selective filtering at strict providers like Microsoft and Yahoo. Anything under 70 triggers spam folder placement, throttling, and outright rejections. Sales teams running cold outreach should target a steady 95 or above and investigate any drop of more than 5 points within a 7-day window.
Is Sender Score still relevant in 2026?
Yes, but with a caveat. Sender Score remains the most widely cited cross-provider reputation grade and is consumed by Microsoft, Cisco, and dozens of corporate filters. Google and Yahoo lean more heavily on their own first-party signals, which is why you should pair Sender Score with Google Postmaster Tools and Microsoft SNDS. Treat Sender Score as the ecosystem-wide health check and the provider tools as the resolution layer when a specific inbox is rejecting you.
How often does Sender Score update?
Validity recalculates Sender Score on a rolling 30-day window and refreshes the public score roughly every 24 hours. A single bad send rarely tanks the score on day one, but a sustained pattern of complaints or bounces will show up within 48 to 72 hours. If you make a corrective change, expect to wait one to two weeks before the score reflects the improvement, because the bad data points need to age out of the window.
Does Sender Score apply to my domain or my IP?
Sender Score is calculated at the IP level, not the domain level. Each sending IP gets its own 0 to 100 grade. If you send from a shared IP pool at a provider like SendGrid or Mailgun, you inherit the pool reputation. If you send from a dedicated IP, your behavior alone drives the score. Domain reputation is a separate signal tracked by Google Postmaster Tools and increasingly by Microsoft, and the two should be monitored together.
What complaint rate triggers a Sender Score drop?
Spamhaus and major inbox providers flag any sustained complaint rate above 0.3 percent as a deliverability risk. Sender Score begins to slide when complaints cross 0.1 percent and falls sharply past 0.3 percent. The fix is to suppress complainers immediately, lower send volume to the affected segment, and pause any campaign generating that complaint level until you fix the targeting or copy.
Can I improve a low Sender Score quickly?
No. A damaged Sender Score takes 30 to 60 days of clean sending to recover because Validity uses a rolling window. The fastest legitimate path is to cut volume by 70 percent, suppress every cold or unengaged contact, send only to recently engaged recipients, and warm the IP back up with low-volume, high-engagement sends. Anyone promising a 7-day fix is misleading you. Sustained behavior change is the only repair.
What is a spam trap and how does it hurt Sender Score?
A spam trap is an email address that exists only to catch senders with poor list hygiene. Pristine traps are addresses that have never opted in anywhere. Recycled traps are abandoned mailboxes that providers repurpose as filters. Hitting either type signals that you are not following permission practices. A single pristine trap hit can drop your Sender Score by 10 to 20 points and land you on Spamhaus SBL.