Mail Tester: Four Products Share the Name, and They Do Different Jobs

"Run it through mail tester before we launch" is a sentence that gets said in a lot of marketing teams, and it is ambiguous in a way nobody notices until the wrong report comes back. Someone searches the phrase, clicks the first result that looks right, pastes in a list of addresses, and returns with a readout on how many of those addresses will bounce. The person who asked wanted a score on the copy they were about to send. The tool that answered was a good tool, and it answered the question it was actually asked.

There are at least four products in this space with near-identical names, run by four unrelated companies, doing three genuinely different jobs. Knowing which one you have open is most of the value.

Four products, one name

Here is the field, with each fact attributed to the vendor page it appears on.

The collision is real enough that one of these vendors disambiguates itself on its own front page. Mailtester.ai's homepage runs a section headed "Two different tests." and tells visitors that most people mix them up, observing that half the results for "email tester" check whether an address is valid while its own product does the other thing.

What mail-tester.com actually does

This is the one most people mean, and it is the one that ranks first. Its homepage headline is "Test the Spammyness of your Emails".

The mechanism is unusual and worth understanding, because it decides what the score can describe. Per the site's FAQ, the service generates a random email address each time you load the page. You send a message to that address from whatever software you actually send with, click the check button, and the report appears once the message arrives.

1. Step 1Open the page

   The site generates a random test address for this run

2. Step 2Send to it

   From the software you actually send with rather than a vendor console

3. Step 3Check the score

   The report appears once the message lands

4. Step 4Read the result

   Scored out of 10, available for 7 days on the free tier

Because you send the message yourself, the test travels your real path: your sending software, your authentication records, your host. That is a genuine strength and it is the reason the tool has stayed the category default.

The FAQ sets the scale plainly: "Your Goal is to Score Perfect 10/10, use our tools to help you get there!" The free allowance is three tests in a rolling 24 hours. Results stay accessible for 7 days on the free version, or 30 days for an account holder using their own prefix. An iframe and a JSON API are described as available on the paid plans.

The detail almost nobody quotes

The FAQ is unusually candid about what is doing the scoring. It describes SpamAssassin as "a widely used spam filter", then adds: "We have a vanilla install. In other words, it's an out of the box default installation. We reversed the score so a positive score is a good score and a negative one is bad."

That single sentence is the correct frame for the whole number. The score is one open-source rule set, in its default configuration, reading your text. It is not a mailbox provider's verdict, and it has no view of your sending domain's history, the receiving gateway your recipient sits behind, or the quality of the list you are about to send to. Those layers are the ones that usually decide B2B placement, and the score cannot see any of them. The argument for why is worked through on what actually triggers a spam filter test, and the underlying term is defined at spam score. A 10 out of 10 is worth having and it forecasts nothing.

What it costs once three a day stops being enough

Pricing lives on the site's manager page rather than a conventional pricing URL, and that page opens on its Monthly tab. The column header reads "Price (excl. VAT)".

A second, non-default tab on the same page sells one-time packs, running from $5 for 10 tests up to $700 for 15,000 tests. Worth knowing before you buy one: the site's terms of service state that "Mail-tester operates on a monthly subscription model" and that "Legacy credits will be phased out over time." The packs are still on display while the vendor's own terms describe them as being retired. Both statements are current on the vendor's surfaces, so read them together and buy accordingly.

MailTester.com is a different company doing a different job

Drop the hyphen and you land somewhere else entirely, and this is the single most common way people end up in the wrong tool. The hyphenated and unhyphenated spellings are not variants of one brand. They are two unrelated companies, and searching the one-word spelling surfaces a different set of products from searching the two-word phrase. If you were sent a link by a colleague, check the address bar before you trust the report.

MailTester.com is operated by Edustria V.O.F. of Beerst, Belgium, per its site footer. mail-tester.com, by contrast, names no legal entity on any page fetched for this article, which is worth registering if procurement is going to ask who they are buying from. Its own pages position it as covering both verification and deliverability in one place, and its homepage describes removing invalid, risky and disposable addresses from a list.

Its email checker page describes four escalating layers on every address, running from syntax validation through domain and mail-exchange lookups to a live SMTP conversation and a screen against disposable and role-account databases. That sequence is the standard shape of the category and it is compared across six vendors on email verification tools, so there is no need to relitigate it here. The homepage advertises 100 free verifications with no credit card required, and claims 99% accuracy. Treat that percentage as a vendor claim rather than a benchmarked result, because no shared benchmark exists across this category.

Its published pricing runs on two models. Credit packs, described as never expiring, include 5K for $19, 50K for $79, 1M for $499 and 10M for $2,999. Subscriptions, on a toggle that defaults to Monthly, include 1,000 verifications a day at $39/mo, 5,000 a day at $79/mo, 10,000 a day at $199/mo and 25,000 a day at $299/mo. The page says yearly billing takes 30% off. It does not publish the resulting yearly figures, so this article does not state them either.

The other two

MailTester.Ninja describes itself as an "Email Checker, Verifier and Finder", which puts it in the same job family as MailTester.com with an email-finding component attached. Its site footer gives a London address.

Mailtester.ai is the odd one out, and the one most likely to be reached by accident. Its homepage headline is "Deliverability testing for newsletter senders", and the mechanism is a forward-to-address flow that returns a score out of 100 along with a Primary, Promotions or Spam prediction. Its homepage prices the scoring at "Free" and zero euros "for unlimited scoring", with €9.99 for its AI deep-dives, and its footer reads "Made in Slovakia". It is aimed at newsletter operators on the consumer sending platforms rather than at B2B cold senders, which is the clearest signal that it is answering a different question from the one a sales team usually has.

Two practical consequences follow from all this. First, a recommendation to "use mail tester" that arrives without a URL is not actionable, and the polite response is to ask which one. Second, the four products fail in different directions, so the failure is quiet rather than loud. A verifier handed a message will not error, and a scorer pointed at a list will not error either. Each returns a well-formatted report about something you did not ask about, and a report that looks finished is much harder to doubt than an error message would have been.

If mail-tester was not the tool you needed

The useful way to pick is by job rather than by ranking. Three jobs get confused with each other constantly, and each one has its own instrument.

Score a messageIs this copy and setup clean?

• A rule engine reads your message and authentication
• mail-tester.com is the category default and free at three a day
• Blind to list quality and to the recipient's gateway

Find out where mail landsWhich folder did it reach?

• Send to a panel of vendor-controlled seed mailboxes
• GlockApps, MailerCheck, MailGenius, Unspam and Saleshandy Inbox Radar sell this
• A score is the wrong instrument for this question

Check an address is realWill this bounce?

• Syntax, MX, SMTP probe and disposable screening
• MailTester.com and MailTester.Ninja sit here
• Run before every send rather than once a quarter

If the question is where your mail lands, no message score can answer it and you want placement testing, which is set up and read differently. That is worked through on inbox placement testing for B2B teams, and the term itself is defined at inbox placement. If the question is whether the addresses are real, you want a verifier, and disposable email covers one of the classes they screen for. Prices for the placement and verification vendors named above are not quoted here unless this article verified them on the vendor's own page.

Which one to reach for

Match the question to the instrument

• ✓Yes: Someone asked whether the copy will trip a filter: message scorer
• ✓Yes: Someone asked which folder the campaign reached: placement test
• ✓Yes: Someone asked whether these addresses bounce: verifier
• ✕No: Someone asked whether the domain is warmed and trusted: none of the three
• ✕No: You want a forecast of campaign performance: no tool here does that

The last two rows are the ones that cause trouble. A perfect score on a message scorer, a clean verification pass and a good placement reading are three separate pieces of evidence, and none of them substitutes for the others. Sequencing them is a large part of running a campaign that actually arrives, which is covered end to end in the cold email deliverability guide.

The short version

Four vendors share this name. mail-tester.com scores a message with a default SpamAssassin install and gives you three free tests a day. MailTester.com and MailTester.Ninja check whether addresses are real. Mailtester.ai scores newsletter placement for consumer sending platforms. Establish which job you are doing before you open the tab, because every one of these tools will return a confident number whether or not it is the number you needed.

If what you actually want is booked meetings rather than a better score, we run the sending side for you: prepay one qualified meeting, and if we do not book it within 30 days you get a full refund.

Pricing and features verified as of August 2026. Verify current terms with the vendor before relying on them.