MailTester.AI
MailTester.AI · Writing · Marketing
MailTester.AI is an AI email tester built for people who hit send and then wonder where the message actually landed. You forward one newsletter, launch, or client note to a one-time test mailbox, and the tool opens it the way inbox filters read it, then predicts whether Gmail, Outlook, and Yahoo will file it under Primary, Promotions, or Spam. It runs a deliverability check across subject line, links, images, merge fields, and SPF/DKIM/DMARC authentication, then hands back three plain-English fixes in priority order. Scoring is free and unlimited, while the AI deep-dive that rewrites your subject, body, and CTA costs credits.
About MailTester.AI
What Is MailTester.AI
MailTester.AI is an inbox placement tester. That's the whole product, and the team is upfront about it. It doesn't validate whether an address exists, and it doesn't run a seed-list test that sends copies to a panel of real mailboxes. Instead, you forward one email to a throwaway mailbox, and the tool reads the content, links, and authentication signals the same way Gmail's filters do, then forecasts the Primary / Promotions / Spam split. One email. One report.
The problem it solves is specific. You spent hours on a campaign, you hit send, and it vanishes into Promotions. Nobody tells you why. MailTester.AI names the three things pushing your email out of Primary, in priority order, so you can fix the send before it reaches your list. It's hosted in the EU (Bratislava), runs GDPR by default, and never keeps your subscriber list.
The main limitation is worth stating plainly: this is a forecast, not a live measurement. It can't see your sending history with Gmail or how your subscribers have engaged with you before, and it doesn't publish an accuracy figure. Each result carries a confidence level instead. The free tier also stops at the score and the three fixes; the full AI rewrite sits behind paid credits.
Getting Started
- Sign-up isn't required to test a send. Grab the test mailbox address the tool gives you.
- Paste that address into the test-send field in Beehiiv, Kit, Substack, Mailchimp, or your own inbox, and hit go.
- The tool opens the copy in real Gmail, Outlook, and Yahoo views and watches which tab it lands in.
- Read the report: a plain-English score, the inbox placement forecast, and the SPF, DKIM, and DMARC server checks.
- Buy credits or a monthly plan only if you want the AI deep-dive, which generates a subject, body, and CTA rewrite in your voice.
Product Information
A quick look at MailTester.AI's pricing, supported platforms, and performance.
Best for
The users, tasks, and scenarios where this tool fits best.
Users
- Newsletter writers on Beehiiv, Kit, and Substack
- Small ecommerce teams running Klaviyo or Brevo campaigns
- Freelancers and agencies sending client notes
Tasks
- Forecasting inbox placement
- Email deliverability checks
- Subject and body rewrites
- Spam score analysis
Scenarios
- Right before a big launch send
- Cleaning up a campaign that keeps landing in Promotions
- Weekly publishing for a paid newsletter
Key features
Inbox Placement Forecast
This is the core of the tool. You forward one email, and MailTester.AI reads the parts inbox filters read: the subject line, the balance of images to text, the links the email carries, and whether SPF, DKIM, and DMARC passed on the copy you sent. It then forecasts the Primary / Promotions / Spam split across Gmail, Outlook, and Yahoo, with a confidence level next to the result. It won't promise you the Primary tab, because no one can, but it shows you what's dragging you toward Promotions.
Plain-English Score and Three Fixes
The report doesn't bury you in deliverability data. You get a score, a verdict in ordinary language, and the three things to change, in priority order. That ordering matters when you're fixing a campaign an hour before it goes out. The homepage demo shows a send scoring 62 that climbs to 91 once the fixes are applied, which gives you a sense of how much headroom a rough email really has. Not every send needs the heavy fixes. Sometimes it's one broken link.
AI Rewrite Bundle
The paid unit is the AI deep-dive. Buy one and the tool generates a subject line, body, and CTA rewrite in your voice, ready to paste back into your campaign. It costs 100 credits per deep-dive. A €4.99 pack gives you 499 credits, or about four deep-dives, while the €9.99/mo Starter plan carries 1,100 credits, roughly eleven a month. This is the only part of the product you ever pay for.
SPF, DKIM, and DMARC Server Checks
Authentication failures sink more sends than most writers realize. MailTester.AI checks all three records on the copy you forward and folds the result into your report. If your domain isn't properly authenticated, you'll see it here rather than discovering it when a whole campaign underperforms. The check comes free with every forward, no credits needed.
Free Email Inbox Tester
Scoring stays free and unlimited, with no account and no card collected. That ceiling is generous for the workflow it serves: you get the verdict, the inbox placement read, and the server checks on every send, forever. The team frames it as free to score, pay for the deep-dive, and that's an honest description of where the line sits.
EU Hosting and GDPR Defaults
The tool is built in the EU and hosted in Bratislava, with GDPR as the default posture rather than an add-on. The test mailbox auto-deletes after your report finishes, and the raw email body isn't stored beyond what the report references: subject line, header metadata, and the classification result. For teams that answer to privacy rules, the data handling is a genuine selling point.
Pros and cons
Pros
- Scoring is free and unlimited, so you can test every send without watching a credit balance.
- Predicts Gmail's Primary / Promotions / Spam split across three major providers, not just a spam score.
- The three fixes arrive in priority order, which is what you actually need before a deadline.
- EU-hosted with GDPR by default, and the test mailbox auto-deletes after each report.
- 30-day money-back guarantee on your first paid month, no questions asked.
Cons
- It's a forecast, not a live inbox test. It can't see your sending history with Gmail or past subscriber engagement, so results can drift from reality.
- No accuracy figure is published, which makes it hard to know how much to trust a marginal score.
- The rewrite that most users want sits behind paid credits, and there's no free trial of the AI deep-dive.
- No public API, so you can't wire the checks into an automated sending pipeline.
Frequently asked questions
It forecasts where your email will land once you press send. You forward a copy, and the tool reads the content, links, and authentication the way inbox filters do, then predicts the Primary / Promotions / Spam split and names three things to fix.
Related content
Explore related tools, skills, and articles for MailTester.AI.
MailTester.AI Alternatives
Google EmbeddingGemma 2
Google DeepMind · Writing · Image · CodingGoogle EmbeddingGemma 2 is a 740M-parameter open model that turns text, code, images, audio, and video frames into vectors in one 768-dimension space, running on phones and laptops.
MePersona
MePersona, Inc. · Writing · Productivity · MarketingMePersona is an AI unified inbox for creators. It learns your voice, drafts replies to fan messages from 12 platforms, and sends only what you approve.
Fluence
Yay Software (Yannick Huchard) · Writing · Voice & Language · ProductivityFluence is an Android app that reads PDFs, EPUBs, Word files and web articles aloud, follows each sentence as it speaks, and answers questions about the text on the phone itself.