Here’s the number that decides whether your outreach works: 0.3%. Google tells senders to keep their spam-complaint rate below 0.1% and never let it reach 0.3% or higher, and since February 2024 it requires anyone sending 5,000+ messages a day to Gmail to authenticate with SPF, DKIM, and DMARC. Cross that line and your emails quietly stop landing.

The catch? You have no built-in way to see that number. Your campaign dashboard says “delivered,” but delivered only means a server accepted the message. It says nothing about whether a human ever saw it.

A free test won’t fix your reputation on its own, I’ll concede that. But it’s the fastest way to find out where you actually stand. In this post, I’ll show you how to run a free email deliverability test, read the results, test your inbox placement across providers, and fix the issues that keep you out of the inbox.

Good news: you don’t have to pay to test your deliverability.

lemwarm’s free email deliverability test (at the top of the page) tells you everything you need to know, such as:

Here’s how to find out about the state of your deliverability:

Step 1: Copy the email address that the deliverability test gives you.

Step 2: Go to the email account you want to test and paste the address in the “To” field.

Step 3: Write the email and send it. The test checks both your overall deliverability and the content of your email.

Step 4: Go back to the deliverability test, check the box, and click “show my results”.

Step 5: Check your results.

Disappointed with the results? Don’t be. It’s a chance to improve your email deliverability before it costs you replies. The test also tells you how to fix what it flags.

Confused by what the results mean? Here’s a plain-language breakdown.

Technical audit results:

Content audit results:

lemwarm’s free test gives you a snapshot, and a snapshot is genuinely useful. But providers judge you over time, and Google and Microsoft each keep their own view of your sender reputation. Where you land with one says nothing about the other.

That’s why I lean on continuous inbox placement testing rather than a single check. lemlist sends to real test addresses across Google, Microsoft, and other providers, then shows whether you’re hitting the primary inbox, promotions, or spam on each one. When a bounce rate spikes or a spam count climbs, you get a real-time alert instead of finding out weeks later when replies dry up.

The Deliverability Hub sits behind this. It rotates your sending across multiple inboxes, caps volume per inbox, and pre-checks a campaign before you hit send. A one-off test tells you today’s score. This keeps you watching the number that decides your inbox placement every day.

lemwarm’s isn’t the only test around. Inside lemlist, you’ll find a feature called Email Tests.

Email Tests checks your deliverability much like lemwarm’s test. There’s one key difference. You can’t use your own emails for testing. Instead, AI generates the emails for you.

Here’s how to test your deliverability with lemlist’s Email Tests:

Step 1: Start your free 14-day lemlist trial by clicking “Sign up for free”.

Step 2: Connect your email account.

Step 3: Click your profile, then “Settings”.

Step 4: Click “Account health”, then “Email tests”.

Step 5: Select the email account you want to check from the dropdown menu.

Step 6: Choose an email to send.

Step 7: Check your results.

The answer you probably expect is: when your score is low. That’s only half true.

The bar isn’t set by you anymore, it’s set by the inbox providers. Yahoo’s sender requirements mirror Google’s for anyone sending at volume: implement both SPF and DKIM, publish a DMARC policy with at least p=none, keep your spam rate below 0.3%, and honor unsubscribes within two days. Break those and your domain reputation slips without warning.

So for any score, you need a tool working behind the scenes to improve your deliverability when it’s low and hold it when it’s high. lemwarm does that by warming your inbox across 20,000+ real domains, and it’s included free with every lemlist plan.

You don’t switch the booster off once your deliverability is good. That would undo the work in no time. Keep it on to maximize the chances of landing in your audience’s inbox.

Deliverability isn’t a one-time fix, it’s a number you watch. Run the free email deliverability test first to see where you stand today, fix whatever it flags in your SPF, DKIM, DMARC, and content, then set up inbox placement testing so you catch the next problem before it reaches a prospect.

Ready to keep every mailbox in the inbox? Start a 14-day free trial and let lemwarm warm and monitor your sending from day one. Prefer a walkthrough first? Book a demo.

Written by Noel, SEO content writer helping B2B brands grow, working remotely from sunny Costa Rica.