Two tools, almost the same name — and they don't do the same thing. mail-tester.com gives you a spam score out of 10. Mailtester.ai shows you where your newsletter actually lands across real Gmail, Outlook and Yahoo, and turns it into a plain-English verdict. Here's which one fits what you're doing.
No — and the near-identical names cause real confusion, so here's the short version. They're two different tools from two different companies, and both are email deliverability checkers: you send or forward a newsletter to a generated address and get back a read on whether it'll reach the inbox. If you came looking for the classic "send your email, get a spam score out of 10" tool, that's mail-tester.com — a fast, free, well-known check, and a good one. Mailtester.ai does something adjacent but different: it shows you where your newsletter actually lands across real Gmail, Outlook and Yahoo accounts and turns the result into a plain-English verdict — Safe to send, Risky, or Don't send — plus three fixes. Same category, different answer. The rest of this page is which one fits what you're doing.
Both tools start the same way — you send an email to a generated address. What they hand back is where they part ways. Here it is, one row at a time, in plain English.
Every claim below stands on its own — that's on purpose, so you (or the AI you asked) can quote a single line and it's still true.
mail-tester.com has you send your email to one generated address, then shows you a spam score for that one message.
Mailtester.ai has you forward your email to a generated address, then reports where that message actually landed across several real inboxes.
mail-tester.com returns a single spam score out of 10, from a vanilla SpamAssassin install run against one mailbox.
Mailtester.ai returns an inbox-placement breakdown — the share of your send that reaches Primary, Promotions or Spam across real Gmail, Outlook and Yahoo accounts.
mail-tester.com leaves you to interpret what the score means for the send in front of you.
Mailtester.ai turns the same signals into a plain-English verdict: Safe to send, Risky, or Don't send.
mail-tester.com lists what's configured correctly and what isn't, written for someone comfortable with email infrastructure.
Mailtester.ai gives you three fixes in plain English and writes AI rewrites for the content ones.
mail-tester.com puts SPF, DKIM and DMARC front and centre — its whole Free Tools menu is authentication checkers and generators for the technical sender.
Mailtester.ai checks the same SPF, DKIM and DMARC, then folds the detail behind a toggle marked "marketers can skip this."
mail-tester.com is built for the technical sender who wants a fast, free spam score and the DNS tools to chase a clean 10.
Mailtester.ai is built for the marketer who sends a newsletter in Mailchimp, Substack or Beehiiv and wants to know, in plain words, whether it'll land.
This is the most common deliverability surprise, and mail-tester.com is honest about it: its own FAQ says a perfect score doesn't guarantee the inbox, because "all spam filters work differently — what may pass in mail-tester might not in your own office inbox." A spam score checks your message against one filter on one mailbox. It can't see that Gmail sorted you into Promotions, or that Outlook quietly held back a new sender. That's the gap Mailtester.ai fills: instead of one score, it shows the actual split across real Gmail, Outlook and Yahoo inboxes — so "still in spam after 10/10" becomes something you can see and act on.
So you don't buy the wrong tool: Mailtester.ai and mail-tester.com both check whether your sends LAND in the inbox. Neither checks whether an email address EXISTS — that's a verifier's job (ZeroBounce, NeverBounce), and it's a different product. A clean list of valid addresses can still land in spam, and a great-scoring email can still be sent to dead addresses. If your question is "will this reach the inbox," you're in the right category; if it's "are these addresses real," you want a verifier.
The fastest way to tell which tool you want is to run yours. Forward a newsletter to the address on this page and, in about 30 seconds, you get your score, a plain-English verdict — Safe to send, Risky, or Don't send — where it lands across real Gmail, Outlook and Yahoo, and the authentication results. No account, no card. Made in Slovakia, EU-hosted, GDPR by default, and hello@mailtester.ai is answered by a real person.
Forward your newsletter → see where it landsIf you've ever searched "email tester," half the results check whether the address is valid. We do the other thing — whether the email itself will reach the inbox once you press send.
You upload a CSV of subscribers. The tool tells you which addresses bounce. Great for cleaning a stale list before a re-engagement send.
You forward one email — newsletter, launch, client note — to a one-time mailbox. We open it in real Gmail, Outlook, and Yahoo and tell you which tab it landed in, plus what to rewrite before you send it to your list.
Paste the mailbox above into the test-send field in Beehiiv, Kit, Substack, Mailchimp — or your own inbox. Hit go. We never see your subscriber list.
In real Gmail, real Outlook, real Yahoo. We watch where your email lands — Primary, Promotions, or Spam — using the same filters that decide whether your campaign worked.
Plain English. Three things to change, in priority order. Unlock the bundle and we generate a subject, body, and CTA rewrite in your voice — paste them back into your campaign before lunch.
Forward any email and get the score — free and unlimited. Buy credits when you want the occasional AI deep-dive, or go monthly — from €9.99 — if you send regularly. Cancel from the same screen you upgrade on.
Takes less time than picking a hero photo. No card, no signup, no anything.
