Why this is worth ten minutes
A newsletter that lands in Promotions still counts as delivered. Your sending platform reports 99% delivery and shows you nothing else. The distance between "delivered" and "read" is where campaigns quietly die, and nothing on your side of the send is looking at it.
Most of what decides that distance is technical, and none of it is visible from where you are standing: a DNS record with a syntax error, a header the receiving server expected and did not find, an IP address somebody else burned last month (a neighbour on shared hosting, or whoever had it before you).
What happens to the message you send
You get a disposable address. Send it the message you were about to send your list: the real one, with the real links and the real sending setup behind it.
It arrives at a mail server that behaves the way a receiving one does. The server verifies your signatures, reads your DNS, asks two independent spam engines what they make of the content, and looks your sending address up in more than twenty blocklists. Nothing to install, and the address works once and expires in an hour.
What the test checks
Hi, I'm Serg.
I built Email Spam Tester because most email testing tools either hide the technical details or want an account before they show you anything useful.
This one gives you a transparent report built on real email authentication, DNS, infrastructure and message checks. Every warning quotes the RFC section it rests on, so you can check my work.
I build and maintain it independently. Most of the checks here started as problems I had to debug on live traffic, during years of running sending infrastructure.
Started in 2026Independent projectPermanent free tier
Reading the report
Two scores. One reproduces what the classic SpamAssassin-based testers give this exact message, so the number is comparable to what you have seen elsewhere. The other is ours, and it covers ground the classic method never looked at: the bulk sender rules Gmail and Yahoo began enforcing in 2024, link reputation, one-click unsubscribe.
Under that, 42 checks with the evidence behind each one. Every warning and every failure carries the section of the RFC it comes from, quoted, and the page where Google states its own requirement. You can check us.
Then a plan for this message: what to change, in what order, and how many points each change is worth (the points are recomputed by scoring the fixed version, not estimated).
What a spam score actually measures
A spam score is a running total of penalties. Every filter rule your message trips adds points, and the classic SpamAssassin threshold is 5. Below it the message passes, at or above it the message is spam. So the scale runs the wrong way round from the one most people expect. A low score is the good one, and the 10 out of 10 that testers show you is a count of the points you did not lose.
The rules doing the counting are unglamorous. An image with no text around it, a subject line in capitals, a From domain whose DNS does not authorise the server the message came from, a link shortener somebody else burned last year. Each rule is worth a fraction of a point, and the points are what accumulate. A message rarely fails on one rule (that would be easy to find), it fails on eleven of them adding up quietly while you were looking at the design, and no single one of those eleven looks like the culprit when you go back to check.
We give two scores for the same message. One reproduces the classic SpamAssassin number, so it is comparable to whatever other spam score checkers have told you. The other is ours, and it counts what the classic number never looked at, which is the bulk sender rules Gmail and Yahoo began enforcing in 2024, link reputation, one-click unsubscribe.
| Our score, 0 to 100 | What the report says |
|---|---|
| 90 to 100 | Ready to send |
| 70 to 89 | Good, with a few fixes |
| 50 to 69 | Needs work before you hit send |
| Below 50 | This will not reach many inboxes |
How to test email deliverability
Send the message you were about to send anyway. Not a two-line draft written for the test. The real one, with the real links and the real platform behind it.
Then check three layers separately, because they fail separately. Authentication is DNS, and SPF, DKIM and DMARC either line up with the server the message came from or they do not. Reputation is your domain and your IP as the receiving side has been recording them, blocklists included. Content is what the filters make of the words, the links, and how much of one there is against the other.
One test is one snapshot. That snapshot describes one send and nothing further, so run the test again after each change. The fix plan recomputes the points by scoring the corrected version instead of estimating what the correction ought to be worth, which means you can see whether anything moved.
Sender score is a different number
Sender score usually means something narrower. It is a reputation rating for one sending IP address, published by Validity on a 0 to 100 scale, and there a high number is the good one. It describes the address you send from across weeks of history, so complaint rates go into it, spam trap hits go into it, and so does volume that jumped on a Tuesday when nothing else about your sending had changed.
A spam score describes one message. The score and the sender score are independent, and they fail independently. Immaculate content from a burned IP lands in spam, and a spotless IP will not rescue a message that trips eleven content rules. Fixing the wrong one is the ordinary way a week disappears.
This tester answers for the message and for the setup behind it. If your reputation is what is wrong, the report says so and names the blocklist, and that is the part you can act on today.
| Spam score | Sender score | |
|---|---|---|
| What it describes | One message | One sending IP address |
| Who works it out | The filters on the receiving server, and this tester | Validity |
| Scale | Penalty points; SpamAssassin's threshold is 5, and lower is better | 0 to 100, and higher is better |
| What moves it | The content, headers, links and authentication of this message | Complaints, spam trap hits and volume over weeks |
| How to improve it | Change the message or its DNS records, then test again | Change how you send, then wait |
From the blog
- Best Email Spam Testing Tools
The email spam testing tools I actually use for real senders, what each one measures, roughly what it costs, and where the one I built fits, bias included.
- Email Blacklist Check: How to Know If Your IP or Domain Is Blacklisted
How DNS blocklists work, which of them receivers actually consult, how to check an IP or a domain by hand, and what to do when you find yourself listed.
- How to Prevent Emails From Going to Spam in Gmail
What Gmail actually weighs, the rules it has enforced since February 2024, and the order I fix things in when a good sender lands in the spam folder.
Questions
Is it free?
Yes. The first 100,000 reports are free for everyone, with no cap per person and no account to make: no signup, no card, no API key. After that, 5 tests per IP address per day stay free for as long as the service runs. This is written into the terms, not a launch offer. When the 100,000 mark gets close, I will say so here and in the changelog well before anything changes.
What counts as a good spam score?
On the classic SpamAssassin scale it is a number below 5, and lower is better, because the score is a total of penalties. We also give our own score from 0 to 100, and that one reads the way people expect, so higher is better. It weights authentication and infrastructure more heavily than the classic number does.
How long does the test address last?
It takes exactly one message and expires an hour after you reserve it. The report link does not expire, so you can come back to it or send it to whoever owns the DNS.
Can other people read my report?
Anyone holding the link can, and the report shows the subject, the sender, the bounce address and the full source of the message. Treat the link as private, and do not test somebody else's mail without asking them first.
How is this different from other spam checkers?
Two scores instead of one, so the classic SpamAssassin number is there for comparison and ours covers what it never looked at, including the bulk sender rules Gmail and Yahoo began enforcing in 2024. Every warning quotes the section of the RFC it rests on, and the fix plan recomputes its points by scoring the corrected message rather than estimating.
Do I need to install anything?
No. You send an email, which is a thing your sending platform already does. There is also an API and an MCP server if you want the same loop from a script or an agent.