Email Spam Test: How to Run One and Read It

What does an email spam test actually check?

An email spam test is a real message sent to an address the testing tool controls. The tool then takes the message apart the way a receiving server would. It doesn't simulate anything. It reads the headers your mail actually arrived with, so the result only describes the sending path you used for that one message. Most testers report on the same handful of things, and each one fails for its own reasons.

Check	What the tester reads	Typical cause of a failure
SPF	Whether the sending IP is authorised by the TXT record on the envelope-sender domain	Your sending service is missing from the record, or the domain publishes two separate v=spf1 records
DKIM	Whether the signature verifies, and which domain signed it (the d= tag)	The selector record isn't published, or the service signs with its own domain instead of yours
DMARC	Whether SPF or DKIM passes and aligns with the visible From domain	DKIM passes, but for a domain other than your From domain
Content rules	Rule hits such as SpamAssassin's, added up to a score	Link shorteners, image-only bodies, mismatched link text and URL, missing plain-text part
Blocklists	Whether your sending IP or domain appears on DNS-based lists	Earlier sending to bad addresses, or a shared IP listed because of other senders
Unsubscribe headers	List-Unsubscribe and List-Unsubscribe-Post	The header is missing, or the one-click URL doesn't answer a POST request

Content rules get most of the attention, but they're the least decisive part for large mailbox providers. Our article on spam trigger words and how filters score them explains why the same phrase can cost points in one filter and nothing in another.

How to run an email spam test, step by step

1. 1 Send from the real path. Use the same From address, the same sending domain and the same service, for example your own Brevo account, that your outreach goes through. A test sent from a personal Gmail account checks Google's setup, not yours.
2. 2 Use the real message. Fill every merge field with a realistic value and keep the same links, images, tracking and signature. A stripped-down test message gives you a clean score for an email you'll never actually send.
3. 3 Send one copy to the tester. Use the tester's address, or its seed list if it offers one. Don't send a string of identical copies: repeated sends of the same message tell you nothing new.
4. 4 Read authentication first. Look for spf=pass, dkim=pass and dmarc=pass in the Authentication-Results header, and check that the DKIM d= domain matches your From domain.
5. 5 Read the content score next. Go through each rule hit and its points rather than the total.
6. 6 Check the blocklist results. Note whether a listing is for the IP or for your domain, because the fix is different for each.
7. 7 Fix the problem and wait out the DNS change. A changed record only shows up once the old record's TTL has expired at the resolver the tester queries. If you test straight away, you may be reading the old record.

If the test shows a pass but replies still dry up, the problem usually isn't in the message. Our guide on why emails go to spam and how to fix it covers the reputation and complaint side, which a single test message can't show.

How do you read the spam score?

A spam score is the sum of the rule hits a content filter recorded. In Apache SpamAssassin, the open-source filter many testers build on, each rule adds or subtracts points, and a message counts as spam once the total reaches the threshold set in the required_score option. Whoever runs the receiving server chooses that threshold, so the same score can pass at one company and fail at another.

Testers also present the result differently. Some show the raw SpamAssassin total, some convert it to their own scale, and some combine it with authentication and blocklist results into one grade. Only compare scores from the same tool. A good grade in one checker and a mediocre one in another can describe exactly the same message.

Chasing a perfect score doesn't help if authentication is broken. Rewriting your copy to remove a few points while DMARC fails alignment fixes the cheap problem and leaves the expensive one in place. Gmail and Outlook rely far more on authentication and domain reputation than on individual words. Fix the header results first, then look at the rule hits.

Free email spam checkers: which tool does what?

The tools ranking for this search fall into two groups. Single-message checkers return a score and a header report for one email. Inbox-placement testers send to a set of seed inboxes at different providers and report where each copy landed. The table uses each vendor's own description from the title of its page in the current search results. Check the vendor's documentation for current features and plan limits before you rely on one of them.

Tool	How the vendor's page title describes it	Question it fits	Limit it shares with the others
mail-tester.com	Newsletters spam test	A spam score for one message, also documented in MailPoet's knowledge base as a way to test your spam score	Sees one message to one test address, with no history of your real recipients
Unspam	Free email spam checker: spam test and spam score	A free score for one message	Same: one message, no recipient history
MailGenius	Mail tester: free email deliverability and spam check	A free deliverability and spam check of one message	Same: one message, no recipient history
MailReach	Free email spam test and checker	A free spam test of one message	Same: one message, no recipient history
GlockApps	Email spam tester: get your inbox insight	Where a message lands across inboxes	Seed inboxes have no engagement history with you
MxToolbox	Email deliverability tool: check your deliverability report	A report on DNS, headers and blocklists	A DNS and header report, not placement in your recipients' inboxes
Constant Contact	Check your spam score (knowledge base)	A spam score inside that email marketing platform	Built for mail sent through that platform

Pick the tool based on your question. If you want to know whether your DNS and headers are correct, a single-message checker or a DNS report is enough. If you want to know which folder a message ends up in at Gmail, Outlook and Yahoo, you need a seed-list test. None of these tools can tell you how your real prospects' mailboxes will treat you, because they've never received anything from you.

What a spam test can't tell you about cold email deliverability

Cold email deliverability is decided by the receiving server, and it weighs things a test message never touches. These include the reputation your domain has built at that provider, the complaints earlier recipients filed, how many addresses on your list bounced, and how much you send per mailbox per day. Google's email sender guidelines ask bulk senders to keep the user-reported spam rate shown in Postmaster Tools low. A tester can't see that rate. Only Postmaster Tools shows it, and only for a domain you've verified there.

In practice, a test can pass on a domain that's already in trouble with Gmail. It can also flag a content issue that a provider with a good reputation record for you would ignore. Treat the test as a check of your setup, not a forecast. Our article on what decides cold email deliverability covers the reputation side in detail.

Does a spam test measure your email deliverability rate?

No. Your email deliverability rate, in the sense of delivery rate, is the share of sent messages the receiving servers accepted, meaning accepted divided by sent. A server can accept a message and still put it in the spam folder, so inbox placement is a separate measure. A spam test sends one message and doesn't measure either rate across a campaign.

You get the delivery side from your sending service's bounce and delivery logs. In your own Brevo account, that's where hard and soft bounces show up for each address. Inbox placement can only be sampled with seed tests. Our explainer on email deliverability rate, delivery versus inbox, separates the two measures and explains why accepted mail can still land in spam.

Should you spam-test a sales follow up email template?

Yes, but test the template the way it will actually be sent: with every field filled in. Content filters score the finished message, so an unfilled placeholder such as an empty first name or a literal curly-brace tag gets scored too. A short, plain template like this one usually has few rule hits:

Hi Anna, following up on my note from Tuesday about onboarding at Northwind. If it's not a priority this quarter, a one-word 'later' is fine and I'll stop here. Otherwise, would a short call next week work? – Jonas

Test it once with the longest company name and job title on your list as well. Long values can break the layout or push a link onto its own line. Our page of sales follow up email template examples has more variants for different stages.

Does a follow up sales email get filtered differently?

A real follow up sales email sent as a reply carries In-Reply-To and References headers that point to the earlier message. That's what makes mail clients thread it. A spam tester receives your follow-up as a fresh message with no thread behind it, so it can't show how the recipient's mailbox treats the thread. Adding "Re:" to the subject doesn't create those headers either. It only changes the subject line.

Follow-ups also count toward your daily volume per mailbox, and each one goes to an address that might have bounced on the first touch. Remove hard bounces before the next step runs. Our guide to email list hygiene for cold outreach covers that check and how to treat catch-all addresses.

Do the best times to send cold emails affect a spam test?

No. A spam filter scores the message and the sender's reputation. The hour you send at isn't a content or authentication signal, so a test sent in the morning and one sent late at night score the same. Timing does affect deliverability in one indirect way: if you push a whole day's volume out of one mailbox in a single burst, that spike in volume is something providers notice.

Spread sends across the window you pick instead of releasing them all at once. Our article on the best time to send cold emails covers days and hours in the recipient's time zone, and why open data can't settle the question.

How EmailFlow OS relates to your spam tests

This section describes a EmailFlow OS product, not one of the tools compared above. With EmailFlow OS, you record one video and upload it, connect your own Brevo account and sending domain, and import your prospect list into EmailFlow OS. EmailFlow OS then creates a personalised version of that recording for each recipient and sends each one from your own inbox, through your Brevo account and your domain. There's no shared platform sender in between.

For spam testing, this means the SPF, DKIM and DMARC records and the domain reputation you test are the same ones your video emails go out on. Whether a message reaches an inbox is still up to the receiving server. You can look up your domain's records with the SPF DKIM DMARC checker on this site. The home page describes personalised AI video email sent from your own Brevo account.

Questions people ask

? How often should I run an email spam test?

Run one after every change to the sending path: a new or edited SPF, DKIM or DMARC record, a new sending service, a new From domain, or a new template. Wait until the old DNS record's TTL has expired before you test again. Between changes, a repeat test on the same setup tells you very little. Watching bounces and Postmaster Tools data tells you more.

? Why does my spam test pass but my emails still go to spam?

A test checks one message's headers, content and blocklist status. Gmail and Outlook also weigh your domain's reputation, the complaints earlier recipients filed, bounce levels and volume spikes, and the tester can't see any of those. A pass means your setup is correct. It doesn't mean real recipients' providers trust your domain yet.

? What is a good spam score?

It depends on the scale. In SpamAssassin, a message counts as spam once its total reaches the required_score threshold the receiving server has set, so lower totals are better. Many testers convert the total to their own grade, and those grades don't line up across tools. Only compare results from the same tester, and read the individual rule hits rather than the total alone.

? Does a blocklist hit in a spam test mean my domain is blocked?

Not necessarily. Check whether the listing is for the sending IP or for your domain. If you send through a shared IP at your email service, an IP listing can come from other senders on that address. A domain listing points at your own sending, and that's the one to act on first through the blocklist's delisting process.