Sender Score: What It Rates and How to Check

What is a sender score?

Sender Score is a reputation number that Validity publishes for individual sending IP addresses. Validity presents it on senderscore.org as a numeric score where a higher value means a better reputation. It rates an IP, not a domain and not a person. If two companies send from the same IP, they share one Sender Score. One company spread across several IPs gets a separate score for each. That's the main thing to know before you read the number. It tells you how mail from that address has behaved recently across Validity's data network. It doesn't tell you how Gmail or Outlook rates your sending domain, and it doesn't decide where any particular message lands. Each receiving server makes that call with its own filters, and Validity's data is only one input that a server may or may not use. A good Sender Score can sit alongside spam-folder placement, and a poor one doesn't mean every message gets blocked.

What goes into a Sender Score?

Validity's description of Sender Score names the kinds of signals behind it. All of them come from how recipients and receiving systems react to mail from the IP:

• Spam complaints: recipients clicking 'report spam' at mailbox providers that share feedback data.
• Unknown users: messages sent to addresses that don't exist and come back as hard bounces.
• Spam-trap hits: mail sent to addresses that exist only to catch senders who use purchased, scraped or stale lists.
• Volume and consistency: sudden spikes from a quiet IP look different from steady traffic.
• Blocklist listings: whether the IP shows up on blocklists that are commonly used.

Most of these come back to list quality. Unknown users and spam traps are almost always a list problem, not a copy problem. That's why bounce handling and re-verification matter more for this number than wording does. Our guide to email list hygiene for cold outreach covers dropping hard bounces before follow-ups and how to treat catch-all results.

How to check your sender score

First, find the IP that actually delivered your mail. Then look it up. People often skip the first step and check their website's IP or their domain's MX record instead. Neither of those sends your outreach.

1. 1 Send a test message from your normal sending setup to a mailbox you control, such as a Gmail address.
2. 2 Open the full headers (in Gmail: 'Show original').
3. 3 Read the Received lines from the top. The relevant IP is the one where the recipient's server says it received the message from your provider's outbound server. For mail sent through Brevo, that's a Brevo IP, not your own server.
4. 4 Check the Authentication-Results line in the same header for spf=pass, dkim=pass and dmarc=pass. A score means little if your authentication is failing.
5. 5 Enter that IP on senderscore.org. If you enter a domain, the lookup works with IPs tied to that domain, which may not be the ones that sent your outreach.
6. 6 Write the result down with the date. One reading is a snapshot. A trend over several weeks tells you more.

Want to check the authentication part without digging through headers? The SPF, DKIM and DMARC checker on this site reads the published DNS records for your domain. Our step-by-step email reputation check for Brevo senders explains where Sender Score fits among the other checks.

Why does my sender score show no data?

An empty or missing score usually means Validity hasn't seen enough recent mail from that IP to rate it. That's common for a cold outreach setup that sends a modest number of one-to-one messages a day, and it's not a warning sign. It's also common for a new dedicated IP that hasn't been warmed yet. Big jumps have their own usual causes. One is a burst of mail to an old list, which brings in unknown users and possibly trap hits at the same time. Another is a new campaign landing on recipients who complain. On a shared IP, a third cause is simply another customer's campaign. In that last case nothing in your own setup changed, and nothing in your setup will fix it. Low-volume senders get more useful information from Google Postmaster Tools, which shows domain-level data for mail to Gmail. Postmaster Tools has its own minimum-volume condition, though, and may also show nothing for small senders.

Sender score on a shared vs. dedicated Brevo IP

Brevo sends most accounts' mail through shared IP pools. In that case the Sender Score you look up belongs to the pool's IP. It's shaped by every sender Brevo routes through that address, and your own behaviour is only a small part of the picture. A high score on a shared IP doesn't prove your practices are clean, and a dip doesn't prove you caused it. If your Brevo account sends from a dedicated IP, the score reflects only your traffic, which makes it a real diagnostic. It also means the IP's reputation depends entirely on your volume and list quality, so a dedicated IP that sends too little or too irregularly can end up with a weak or empty score. In both cases, the reputation that follows you is the one tied to your own sending domain. Mailbox providers increasingly weigh domain reputation, and your domain stays with you if you ever change IPs. Our article on sender reputation explains how IP and domain reputation differ and which one to fix first.

Which tools check sender reputation besides Sender Score?

Sender Score is one lookup among several. Each of these tools answers a different question. Here they're compared on what they rate, where their data comes from and who can see it.

Tool	What it rates	Data source	Who can look it up	Where it stops
Sender Score (Validity, senderscore.org)	Individual sending IPs, as a numeric score where higher is better	Validity's reputation network	Anyone, for any IP	No domain rating; on a shared IP it reflects every sender on that IP
MxToolbox blacklist check	Listing status of an IP or domain across many blocklists, including the Sender Score reputation network	The blocklists it queries	Anyone	Shows listings, not a reputation trend; a clean result says nothing about spam-folder placement
Spamhaus reputation checker	Domains and IPs	Spamhaus's own data	Anyone	Only Spamhaus's view; other mailbox providers use their own data
Google Postmaster Tools	Domain and IP reputation for mail sent to Gmail	Gmail's own traffic	Only the verified domain owner (DNS TXT verification)	Gmail recipients only; shows little or nothing below its volume threshold
Microsoft SNDS	IP data for mail to Outlook.com consumer mailboxes	Microsoft's own traffic	Whoever can prove control of the IP	IP-based; on a shared Brevo IP you generally can't register the address

If a lookup shows a listing, the next step is to find out which list it is and what that list's removal process requires. Our guide to email blacklist checks and removal goes through it list by list.

How do you raise a low sender score?

Since the score follows recipient reactions, the fix is to change what you send and who you send it to. Then wait for new data to replace the old. Here's what works, in order:

1. 1 Stop sending to the segment that caused the drop. Usually that's an old or bought list.
2. 2 Remove every hard bounce and every address that complained. Re-verify the rest before you import it again.
3. 3 Keep volume steady instead of trying to catch up with one big send.
4. 4 Confirm that SPF, DKIM and DMARC pass and that DKIM aligns with your From domain.
5. 5 Re-check the IP over the following weeks rather than daily.

What doesn't work: switching to a fresh IP to escape the number. The new IP starts with no history, and the problems that caused the drop come along with you, along with your domain. Sending 'good' mail to engaged contacts to pad the average doesn't work either if the problem list is still in rotation. And on a shared Brevo IP, none of these steps will move a score that someone else's traffic is driving down. Your own effort there should go into domain reputation and your bounce and complaint numbers.

Where EmailFlow OS fits

EmailFlow OS is a personalised AI video email product for B2B cold outreach. It doesn't change how any reputation service scores you. What it does change is whose reputation your outreach builds. You record one video and upload it to EmailFlow OS, connect your own Brevo account and sending domain, and import your prospect list into EmailFlow OS. EmailFlow OS then makes a personalised version of that one recording for each recipient, not just each company. Every version goes out from your own inbox, through your Brevo account and your sending domain, never through a shared platform sender. That keeps the bounce, complaint and authentication results tied to a domain and a Brevo account that you control and can inspect with the tools above. The home page has more on how personalised video outreach from your own Brevo account works.

Questions people ask

? What is a good sender score?

On Validity's scale, a higher number means a better IP reputation. But 'good' depends on whose IP it is. On a dedicated IP, the number reflects your own sending. On a shared Brevo IP, it reflects everyone on that pool, so a high score there doesn't confirm your practices. Judge it alongside your domain data in Google Postmaster Tools.

? Is sender score the same as sender reputation?

No. Sender Score is one vendor's rating of one IP address. Sender reputation is the broader judgement each mailbox provider forms about your IPs and your domain from its own data. Gmail and Outlook weigh their own signals, so you can have a strong Sender Score and still see spam-folder placement at a specific provider.

? Can I check sender score for a domain instead of an IP?

Sender Score itself rates IPs. A domain lookup on senderscore.org works with IPs tied to that domain, which may not be the IPs that sent your outreach. To rate the domain itself, use Google Postmaster Tools after DNS TXT verification, or Spamhaus's domain reputation checker, which covers domains as well as IPs.

? Does sender score affect cold email deliverability?

It can indirectly, if a receiving server consults Validity's data. Each server applies its own filters, though, and also checks SPF, DKIM and DMARC alignment, domain reputation, bounces and complaint rates. A score is a symptom to read, not a setting you control. Fixing list quality and authentication changes what feeds it.