A clean list gets you to the door. This gets you inside.
Verification removes the addresses that bounce. The inbox tester shows what happens to the rest: provider by provider, does your campaign land in the inbox, the promotions tab, or spam — and why.
“Delivered” doesn't mean “seen”
Your ESP reports 99% delivered and your open rate still sinks. That's because delivered counts the spam folder. Without placement data you're optimizing subject lines while the real problem is which folder you land in.
Spam placement is invisible to you
No bounce, no error, no warning. Your message simply lands where nobody looks — and every standard metric says the send succeeded.
Authentication breaks silently
An expired DNS record or a misaligned DKIM signature after an infrastructure change can route entire campaigns to spam — and nothing in your ESP will tell you.
Blacklists don't send a memo
Your domain or IP can be listed today because of one bad send last week. Most senders find out from collapsing open rates, weeks later.
Real seed inboxes at the providers that matter
You send your actual campaign — same template, same sending setup — to our seed list. Real mailboxes at Gmail, Outlook, Yahoo, iCloud and 20+ providers report which folder it reached: inbox, promotions, or spam. Not a content-score simulation. The real verdict, from the real providers.
- Per-provider breakdown: inbox / promotions / spam, side by side
- Test the exact campaign you'll send, from your own infrastructure
- Results within minutes of the send reaching the seeds
Authentication diagnostics in plain English
Every test inspects how your mail authenticates in the wild: SPF, DKIM and DMARC are checked on the actual received messages, not just your DNS records. When something is missing or misaligned, you get the specific fix — not a cryptic acronym soup.
- SPF, DKIM and DMARC verified on real received mail
- Alignment problems explained with concrete next steps
- Catches breakage from ESP migrations and DNS changes
Blacklist monitoring that never sleeps
Between tests, we watch the DNSBLs that measurably affect delivery — Spamhaus, Barracuda, SpamCop, SORBS and more — for your domains and IPs. The moment a listing appears you get an alert with a delisting playbook, so you fix it before your subscribers notice anything.
- Continuous checks across the blacklists that actually matter
- Instant alerts on new listings, with per-list delisting guidance
- Monitor multiple domains and IPs from one dashboard
Three steps, no learning curve
- 01
Send to your seed list
We give you a list of seed addresses — add them to your next campaign like any other recipients.
- 02
We watch every mailbox
Within minutes, each seed reports which folder your message reached and what the provider made of your authentication.
- 03
Fix, re-test, compare
Each issue comes with a concrete fix. Re-run the test after changes and compare placements side by side.
- 20+
- mailbox providers covered
- 25+
- seed mailboxes per test
- 24/7
- blacklist monitoring between tests
- 3
- folders tracked: inbox, promotions, spam
The full deliverability picture
Provider-by-provider map
Gmail might inbox you while Outlook junks you. See each provider separately and prioritize the fix that moves revenue.
SPF / DKIM / DMARC checks
Authentication verified on real received mail, with plain-English fixes when something is broken or misaligned.
Blacklist alerts
Instant notification when your domain or IP appears on a list that matters — with the delisting playbook attached.
Run-over-run comparison
Deliverability work finally gets a feedback loop: change one thing, re-test, and see the placement shift.
Content factor analysis
The template elements correlated with promotions or spam placement, identified per provider.
Reports you can forward
Clean, shareable reports that explain placement to a client or an executive without translation.
Who runs placement tests
Email marketers
Test the template before the full send. Fix the Gmail promotions problem while it's still cheap.
Agencies
Prove placement to clients with provider-level reports — before and after your fixes.
Teams migrating ESPs
Verify SPF, DKIM and DMARC survived the move before the first real campaign goes out.
Cold outreach teams
Monitor domain reputation continuously — outbound lives and dies by inbox placement.
When I signed up for MailTester.com, I was a bit skeptical at first. How much difference can it make for a relatively smaller company like us? Answer: a lot. We didn't change our email strategy much, still our email open rate has increased like 3-4%. I recommend MailTester.com.
How does inbox placement testing work?
A placement test works by giving the providers themselves the final word. You add a set of seed addresses — real mailboxes we control at Gmail, Outlook, Yahoo, iCloud and other providers — to a campaign and send it exactly as you normally would. As the message arrives at each seed, we record which folder the provider filed it in: inbox, promotions/other tabs, or spam.
Because the test rides on your real sending infrastructure, it captures everything that influences placement: your domain and IP reputation, your authentication setup, your template content, even your sending patterns. That's what makes it diagnostic rather than decorative — when placement shifts, the report shows which factor moved.
Placement testing and verification work together
List verification and placement testing solve the two halves of one problem. Verification ensures you only send to mailboxes that exist — keeping your bounce rate, and therefore your reputation, intact. Placement testing measures what that reputation currently buys you at each provider, and what's holding it back.
Healthy programs run both on a rhythm: verify the list quarterly and before big sends, test placement before major campaigns and after any infrastructure change. MailTester bundles them — subscriptions include placement reports and blacklist monitors alongside verification credits.
Pay only for what you verify
Credits from $19, volume rates down to $0.0003 per email — and they never expire. Subscriptions bundle inbox testing and monitoring.
How many emails do you need to verify?
50,000credits
$79
$0.0016 per email
Common questions
Stop guessing which folder you land in.
Run your first placement test and get a provider-by-provider map of your deliverability.