If you're sending cold emails or running email marketing, you need to know where those emails actually land.
Studies put average inbox placement at about 85%. So 15 out of every 100 emails you send never reach the inbox, and nothing tells you which ones.
Email spam checker tools should catch that before you hit send. But most of them only cover part of the problem.
You pay for one tool to score your content, another to watch your domain, and a third to test where your emails land. That's three subscriptions for one job.
These are the complaints I hear most from cold email and email marketing teams:
I tested the email spam checker tools people recommend most and kept the 10 worth using. Let's look at each one in detail.
I didn't rank these tools from their feature pages. I ran the same test through each one.
I ran the same 3 templates through every tool over three weeks, and checked each verdict against 15 inboxes I control. I haven't tested every enterprise tier, so I can't speak to those.
Prices come from each vendor's pricing page while writing this blog post. Here's the detail on each tool, starting with my top pick.
G2 Rating: 4.6 out of 5
Best for: GTM teams and agencies who want placement tests, health monitoring, and warmup in one tool.
Warmforge is an email deliverability tool. It checks where your emails land, monitors your domain health, and warms your mailboxes, all from one dashboard.
I've kept it at number one for a simple reason. Every other tool here tells you about a problem. Warmforge also fixes the cause, because warmup builds the sender reputation that keeps you out of spam.
You run a placement test, and Warmforge sends your email to seed inboxes at Google, Outlook, and other major inbox providers. That report shows if it landed in the primary inbox, the promotions tab, or the spam folder.
In my testing, I ran a placement test before a 3,000-contact send and caught the template landing in promotions on Gmail. I removed two links and a tracking pixel, retested, and it landed in primary.
Annual billing takes 10% off, and the Growth plan gives you two months free.
The one limitation I'd flag: each slot includes 1 free placement test a month. I test before every campaign, so I'm on a Placement Test plan. If you only spot-check occasionally, the free allowance covers you.
You can create a free Warmforge slot here and run your first placement test today.
G2 Rating: 4.2 out of 5
Best for: Marketing teams and agencies that need placement advanced reports with other deliverability metrics.
The next tool on my list is GlockApps. It is an email deliverability tester, and one of the oldest names in inbox placement testing.
You send your email to their seed list. Its report shows where it landed at every provider: Gmail, Outlook, Yahoo, and dozens more.
In my testing, the Gmail tab prediction stood out. It told me my HTML-heavy template would land in the promotions tab before I sent anything real.
But know this before you buy. GlockApps finds your inbox placement issues, and it stops there. There's no warmup, no infrastructure, and no sending, so you need other tools to fix what it finds.
Also watch the credit system. Unused test credits expire at the end of each month with no rollover.
Custom plans are available for high-volume senders.
G2 Rating: NA
Best for: Solo senders and small teams who want a free content and authentication check before a one-off send.
The next tool is Mail-Tester, and it's the one most people try first. You send a test email to a unique address, refresh the page, and see your score out of 10. The whole thing takes under a minute, and you don't need an account.
Its report covers your SpamAssassin score, your SPF, DKIM, and DMARC setup, blacklist status, and broken links.
When I misconfigured authentication on a new domain, Mail-Tester caught it faster than anything else here.
But a high score is not placement. In my testing, an email scored 9 out of 10 on Mail-Tester and still landed in spam, because placement depends on sender reputation, not just content. A high score means your email looks clean. It doesn't mean Gmail will show it in the primary inbox.
One more thing: free test results stay visible to anyone with the test URL for 7 days.
One-time payment options are also available if you don't want a subscription.
G2 Rating: 4.7 out of 5
Best for: Cold email teams and solo senders who want warmup and spam testing from one vendor.
The next tool on my list is MailReach. It is a warmup tool with a spam tester built in. That makes it the closest thing to Warmforge on this list.
Its spam test works the same way. Your email goes to a network of real inboxes, and you see where it lands at each provider.
You can buy the spam tester on its own, or take the All-In-One plan that bundles it with the email warmer.
In my testing, the placement test was accurate and the deliverability report was easy to read. The checks that come with it are thorough too, covering reverse DNS, blacklists, links, and spam words.
The catch is the cost per test. MailReach sells spam tests as credits, and 300 credits cost $175.50. That works out to about $0.59 per test, against $0.33 per test on Warmforge's Placement Test Pro plan.
G2 Rating: 4.6 out of 5
Best for: Marketers who want an audit that explains every problem it finds and how to fix it.
The next tool is MailGenius. It is a content and authentication audit tool. You paste or send your email, and it scans for spam trigger words, authentication problems, and technical issues that hurt inbox placement.
I like the way it explains things. You don't just get a score. You get a list of specific problems, each with a fix in plain language.
If you're new to deliverability, those explanations are worth more than the score.
Its AI consultant goes a step further and rewrites your copy, which none of the other content checkers here do.
The spam test is free to run. Paid plans start at $23 a month and go up to automatic testing on every email you send.
G2 Rating: 4.8 out of 5
Best for: Cold emailers and newsletter senders who want a free spam score and a design check in one place.
The next tool is Unspam. It is a free spam checker that runs an email spam test in about 30 seconds. It checks your SPF, DKIM, and DMARC records and your blacklist status.
It adds two things no other tool here offers. An AI eye-tracking heatmap predicts where readers will look in your email, and email client previews show how it renders across 50+ real clients and devices.
Its free tier is the most generous on this list. You get 10 spam tests, 3 inbox placement tests, 10 email previews, and 10 heatmaps a month, with no card. Your results stay private, unlike Mail-Tester's public test URLs.
The heatmap helps on design-heavy emails. For plain-text cold email, it doesn't add much.
Annual billing gives you two months free, and every paid plan has a 14-day refund.
G2 Rating: 4.6 out of 5
Best for: Developers who want free, unlimited spam scoring through a web page or an API.
Postmark Spam Check is the simplest tool on this list. You paste your raw email and get a SpamAssassin score with a rule-by-rule breakdown. That's it.
It's free, it has no test limits, and it has an API. Developers can add spam scoring to a build pipeline or a pre-send check. I keep it bookmarked for quick checks.
There's no placement data, no monitoring, and no account. It does one job instantly and charges nothing.
Postmark also sells a transactional email platform, which is a separate product with its own plans.
DMARC monitoring is an add-on from $14 per domain per month.
G2 Rating: 4.8 out of 5
Best for: Sales and marketing teams that want a team to manage their deliverability for them.
Folderly is two tools under one name. The first is a free AI spam words checker. You paste your subject line and body, and it flags risky wording before you send. The second is a paid email deliverability platform where Folderly's team also manages your deliverability for you.
Its free checker is a good first stop for content checks. It also gives away Pulse, which sends real-time spam placement alerts by email, Slack, and SMS at no cost.
The platform is a bigger commitment. At $96 per mailbox per month, it only makes sense if you want a team actively working on your deliverability.
Placement testing is a separate product called Inbox Insights, with a free tier of 2 tests a month.
G2 Rating: 4.8 out of 5
Best for: Dev teams testing transactional emails in staging before they go to production.
The next tool is Mailtrap. It is an email sandbox for developers with spam analysis built in. Your test emails go to a fake SMTP environment instead of real inboxes, so password resets and receipts never reach a customer while you're still building.
Along with the spam score, you get an HTML checker and client previews. It's a development tool, not a marketing tool.
If you send cold email, this isn't for you. If you build products that send emails, it probably is.
Annual billing saves up to 20%. These are Email Sandbox prices, and Mailtrap's sending product bills separately.
G2 Rating: 4.5 out of 5
Best for: Marketing teams that ship design-heavy email every week and need full QA, not just a spam check.
The last tool on my list is Litmus. It is an email QA suite for email marketing teams. It works with any email marketing platform and checks marketing emails before they go out. Spam testing is one feature next to rendering previews across 100+ clients, collaboration tools, and analytics.
Its previews are the best in the business. If your team ships design-heavy campaigns every week, the QA workflow is worth paying for.
Litmus doesn't publish its prices. You request a quote, which tells you who it's built for. If you only need a spam check, everything else on this list costs less and takes less time to buy.
Most "best spam checker" lists mix three different tool types without telling you. Here's the split.
I ran tests on every tool here, read through their reports, and checked what cold email communities say about each one.
Here's the process, whichever tool you pick.
One thing content checkers won't tell you: placement depends on your sender reputation as much as your copy. That's why I run a placement test through Warmforge before every campaign instead of trusting a content score.
The score checks the email. The placement test checks the email, the mailbox, and the domain together. Fixing what each report flags is how you improve email deliverability over time, not just pass one test.
So far, you've read about ten top email spam checker tools. As you can see, each one is good at a different part of the job.
If the question is which tool I'd run before my next campaign tomorrow, the answer is Warmforge. It shows where emails land instead of guessing from your copy. Health Checks watch DNS, MX, and blacklist status in the background. And warmup fixes the sender reputation that put you in spam, which nothing else here even tries to do.
That's the obvious pick.
One tool. One bill. Placement, monitoring, and warmup in the same place. And if you already run Salesforge, it's included with unlimited slots.
The free slot and free placement test cost nothing and test these claims against a real campaign. A better use of ten minutes than reading another "best of" article.
Warmforge is the best email spam checker for cold email senders in 2026. It combines Inbox Placement Tests, Health Checks on DNS, MX, and blacklists, and Heat Score™ reputation tracking with the warmup that fixes the underlying problem. Mail-Tester is the best free option for quick content checks.
Yes, two ways. A content checker like Mail-Tester scores your email content against spam filters before you send. An inbox placement test like Warmforge's goes further to test deliverability for real: it sends your email to seed inboxes and shows whether it lands in primary, promotions, or spam at each provider.
Yes, several. Mail-Tester gives you 3 free tests a day, Postmark Spam Check is free with no limits, Unspam includes 10 free spam tests and 3 placement tests a month, and Warmforge includes 1 free warmup slot with a free placement test every month on signup.
Run a blacklist check. Warmforge's Health Checks monitor blacklist status automatically on every connected mailbox and alert you when a listing appears. Mail-Tester, MailReach, and GlockApps also include blacklist checks in their reports. If you find a listing, most blacklists have a delisting request process on their site.
A spam score rates your email content and setup against filter rules. Inbox placement is where the email actually lands, which also depends on your sender reputation, sending IP, reverse DNS, domain age, and volume patterns. An email can score 9 out of 10 on content and still land in spam. Placement tests measure the real outcome.
Run a placement test before your next campaign goes live, whenever you change a template, and weekly if you send at volume. Reputation shifts over time, so a template that landed in the primary inbox last month can start landing in the promotions tab. Continuous monitoring through Health Checks covers you between tests.
