Forward your newsletter and get a plain-English verdict — Safe to send, Risky, or Don't send — plus where it lands across real Gmail, Outlook and Yahoo. Free, about 30 seconds.
Search 'spam checker' and you get a wall of tools that all do the same thing: forward an email, get a number back. A number is a fine start — but on its own it doesn't tell you whether to hit send. Here's everything Mailtester looks at when you forward a newsletter, and the one thing it gives you that a bare score can't.
We forward your email into real Gmail, Outlook and Yahoo accounts and watch where it goes: the main inbox, the Promotions tab, or Spam. You get the split as a percentage, not a hunch — because 'it looks fine to me' and 'it reached my readers' are two very different things.
SPF, DKIM and DMARC are how Gmail and Outlook confirm a message claiming to be from your domain actually is. Missing or misaligned, you look forgeable — and forgeable mail gets filtered. We check all three and give you a plain pass or fail. You don't have to read a DNS record: that panel is folded away for the developer or IT person on your team, and marketers can skip it.
Heavy images with little text, a wall of links, link shorteners, a subject line that reads like a sale — filters treat all of these as 'looks like bulk marketing.' We read your actual message the way a filter does and point you at the specific things worth fixing, in plain English. No guessing which word was the problem.
Yes, you still get a score — the same kind other tools give you, built on the same signals (many read SpamAssassin, and it's a real, useful measure). The difference is what we do with it: we don't hand you a number and leave you to work out what it means.
Every other checker on the first page of Google hands you a number out of 10 or 100 and lets you work out what it means for this particular send. Mailtester turns the same signals into a plain-English verdict: Safe to send, Risky — don't send yet, or Don't send. You came to find out whether your newsletter is going to land. That's a yes-or-no question, and we answer it as one.
This one is for the email you are about to send, not one that landed in your inbox. Forward it and we read the message the way a filter does. But copy is one input of several, and it is worth being straight about where it stops.
The subject line gets read on its own terms: trigger words, shouting capitals, runs of punctuation, a pile of emoji, and how long it is. The same reading then runs across the body — plus two things most checkers skip. Whether your images carry alt text, because a newsletter that is one big picture reads as bulk to a filter and as blank to anyone who has images switched off. And whether the visible text of a link matches where the link actually goes: a mismatch is one of the oldest phishing tells, and filters treat it that way even when nothing was meant by it.
Three things, and they weigh more than the words: your domain's sending history, whether your list opens what you send, and how fast your volume has changed. None of that is in the text. A clean subject line will not rescue a domain that has spent a year mailing dead addresses. Copy is simply the input you can fix this afternoon, which is why it is worth checking first — and if it comes back clean and your mail still gets filtered, the cause is further upstream.
Prefer to paste the text rather than forward a whole email? Two sibling checks take it directly — one for a subject line or a block of copy, one for your HTML. Both free, neither needs an account. This page wants the whole email, because forwarding is the only way to read the content and the authentication in one pass.
Forward a newsletter to the address on this page. In about half a minute you get your score, the plain-English verdict, where it lands across Gmail, Outlook and Yahoo, and the authentication results — no card, no trial clock. One honest caveat: we check whether your sends LAND, not whether an address EXISTS. That's a verifier's job, and it's a different tool. If your newsletter's job is to reach real readers, this is the check you want.
Forward your newsletter → run the free checkIf 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. Free, and no card at any point.