What Is Sender Score? How Validity Rates Your Sending IP

Sender Score is a number from 0 to 100 that Validity assigns to a sending IP address, based on how that IP's mail performs compared with every other IP in Validity's data. Zero is the worst and 100 the best. In most cases it is a rolling 30-day average. It is a useful outside view of an IP's reputation, but it is Validity's score, not Gmail's or Microsoft's.

That last point is where most of the confusion comes from. This post covers what goes into the score, how to read it, and how it relates to the reputation data the mailbox providers publish themselves. Everything below comes from Validity's own pages, checked on 7 October 2026.

What the number actually is

Sender Score ranks your IP against other IPs. It is not a percentage of anything. On its mission page, Sender Score says: "All scores are based on a scale of zero to 100. Zero is the worst, and 100 is the best possible score." It adds: "Your score represents an IP address measured against other IP addresses, much like a percentile ranking," and "In most cases, scores are calculated on a rolling 30-day average."

Three consequences follow:

• It is relative. An 85 means the IP looks better than most of what Validity observes. It does not mean 85% inbox placement, and it can move when other senders get better or worse even if you change nothing.
• It is slow. A 30-day window means a bad week lingers for about a month, and so does the recovery.
• It is per IP. A domain sending from several IPs has several scores. On a shared IP, the score is the combined behaviour of everyone using it. That is one of the trade-offs covered in shared versus dedicated IPs.

Where the data comes from

The score is built from data supplied by mailbox and security providers in Validity's network. The get-your-score page says it is calculated using data from the Validity Data Network, "a collection of more than 80 mailbox and message security providers around the globe." Validity does not publish which providers those are, so you can't tell from the score which receivers are seeing the problem.

The mission page defines the main components, which Validity calls indices:

Index	Validity's definition
Complaints	How the IP's complaints compare with all other IPs. "Complaint rates are calculated as complaints divided by accepted mail."
Unknown users	The rank of the IP's unknown-user rate, "taken directly from incoming SMTP logs of participating ISPs", tracking "how often an IP address attempts to send a message to an address which does not exist"
Rejected	"How often messages are rejected (meaning they bounced due to some policy reason, usually spam filtering or blocklisting)"
External reputation	How the IP compares on "a variety of external blocklists and allowlists"
Volume	"Not inherently good or bad, but it's an important part of the overall reputation algorithm"

The get-your-score page lists the factors in a report as blocklists, complaints, infrastructure, sender rejection, messages filtered, spam traps, mailbox provider spam rate, unknown users and send volume fluctuations. Validity does not publish how the factors are weighted, so you can see which ones look bad, but not exactly how much each one counts towards the final number.

Reading the bands

Validity's own bands are Poor below 70, Fair from 70 to 80, and Good above 80. These come from the get-your-score page:

Score	Validity's label	Validity's wording
0 to 70	Poor	"You need to repair your email reputation"
70 to 80	Fair	"You have a fine IP reputation score, but there's room for improvement"
80+	Good	"A history of healthy sending habits has resulted in a great email reputation"

Read the band together with the index breakdown, because the cause decides the fix. A low score driven by complaints is about who you're mailing and whether they asked for it. A low score driven by unknown users is about list quality. A low score driven by external reputation means you need to find out which blocklist has you. Spamhaus is the most common one to check, and the codes are explained in Spamhaus lists explained.

The unknown-user index is the easiest one to fix

Of all the inputs, unknown users is the one you control almost entirely before you send. Validity measures it from the SMTP logs of receiving providers: every time your IP tries to deliver to a mailbox that doesn't exist, that counts against you, compared with every other IP.

That is the same event as a hard bounce on your side. A list that hasn't been mailed for a year, or was bought, scraped or imported from an old CRM, will push the index up on the first send. Removing invalid addresses before the send takes them out of the input. Our guide to calculating your bounce rate shows how to measure where you stand. SimpleVerifier is one way to do the cleaning: it checks each mailbox over SMTP for a flat $29.99 a month and marks catch-all domains as risky rather than valid.

Verification does nothing for complaints or spam traps designed to look like real mailboxes. It addresses one index, not the whole score.

How to look it up

You check Sender Score at senderscore.org, and the lookup asks for contact details first. The get-your-score page takes an IP address or domain. Before it shows a result, the form asks for your first and last name, company name, work email, annual email volume and country, and acceptance of the privacy policy.

You need your actual sending IP, not your website's IP. If you send through an email platform, send a message to a mailbox you control and open the raw headers. The Received line that your own mailbox provider added, usually the top one, names the IP that connected to it.

What Sender Score is not

Sender Score is an outside estimate, and it does not decide whether your mail is delivered. The mission page says so directly: "Sender Score does not directly block or accept email. Receiving email networks and ISPs may query Sender Score and use the result as a means of assessing their email traffic and allowing or rejecting email." Validity says receivers may use it. It doesn't name any that do.

The largest mailbox providers publish their own view of you, and that is the view that counts at those providers:

Source	Whose data	Scope	What it shows
Sender Score	80+ providers in Validity's network	Per IP	A 0 to 100 rank against other IPs, plus index breakdown
Google Postmaster Tools	Gmail only	Per domain you verify	Spam rate, compliance status and delivery errors for mail to Gmail. See reading Google Postmaster Tools
Microsoft SNDS	Outlook.com only	Per IP you prove you're responsible for	Microsoft's SNDS gives "detailed data about individual IPs" for reputation at Outlook.com, after you sign in with a Microsoft account and request access to your IPs

Google's Email sender guidelines say nothing about Sender Score. They set out Gmail's own rules, which we compare with Yahoo's in the Gmail and Yahoo bulk sender requirements.

In practice, these sources often disagree. A good Sender Score with a high Gmail spam rate in Postmaster Tools means Gmail recipients don't like your mail, whatever the wider network sees. A poor Sender Score with clean Postmaster data may mean the problem is at providers other than Gmail, such as a blocklist used by corporate filters. Use Sender Score to spot trends and to see a breakdown the mailbox providers don't give you. Use the providers' own tools to decide what to fix for the providers you send to most.

The practical takeaway

1. Find your real sending IP from a message header, and look up that IP, not your domain's web server.
2. Read the bands as a rank: under 70 needs work, 80 and above is good, and none of it is an inbox rate.
3. Use the index breakdown to choose the fix: complaints mean consent and targeting, unknown users mean list hygiene, external reputation means a blocklist.
4. Allow about 30 days for a fix to show, because the score is a rolling average.
5. Check Postmaster Tools and SNDS as well, because Gmail and Outlook.com rely on their own data, not Validity's.