Email deliverability test – see where your emails actually land

How the test works

The tool generates a set of seed addresses across Gmail, Outlook, Yahoo, ProtonMail, and other major providers. You send your email to those addresses from your real sending inbox, the same one you use for actual campaigns. Ten to fifteen minutes later, the tool checks each seed inbox and tells you whether your message landed in the primary inbox, the spam folder, the promotions tab, or never arrived at all.

The tracking code you paste into the email body is how the tool matches your send to the right test. Without it, results from different senders would mix together. The code goes anywhere in the body. A single line at the bottom works fine.

This is a send-test, which makes it different from a paste-and-score spam checker. A spam checker reads your content and estimates a risk score. This tool actually sends the email and reports what each provider did with it. The difference matters because two senders with identical email content can get completely different placement results depending on their sender reputation, IP history, and domain age.

What the results tell you

Per-provider placement

The most direct signal. If Gmail routes you to spam and Outlook puts you in the inbox, the problem is almost certainly your Google sender reputation, not your content. If every provider flags you, the issue is broader: usually authentication, a blacklisted IP, or a sending domain with no warmup history.

Gmail’s spam filter and Outlook’s are not the same system. Gmail weighs engagement signals heavily, including open rates, reply rates, and how often recipients mark your domain as safe. Outlook puts more weight on IP reputation and SPF/DKIM alignment. A result that splits across providers is useful because it narrows down where the problem actually lives.

Authentication verdict

SPF, DKIM, and DMARC all need to pass for providers to treat your domain as trustworthy. A failing DKIM check means the provider can’t verify the email came from where it claims to have come from. A missing DMARC record means you haven’t told providers what to do with emails that fail authentication, which some providers treat as a red flag on its own.

Google announced in February 2024 that bulk senders (over 5,000 emails per day to Gmail addresses) must have DMARC configured, with SPF and DKIM both passing. Senders who didn’t comply saw delivery rates drop. Authentication is no longer optional.

Content score

The content analysis checks for phrases and patterns that spam filters flag consistently: excessive link density, image-to-text ratio problems, spam trigger words in subject lines, and HTML formatting issues. A high content score doesn’t guarantee inbox placement because sender reputation matters more, but a bad content score will override a good reputation.

Blacklist status

If your sending IP or domain appears on a major blacklist like Spamhaus, Barracuda, or SURBL, most receiving servers will reject or spam-folder your email before any other checks run. The tool checks against the main public blacklists and flags any listings. Being listed doesn’t always mean you did something wrong. Shared IPs on email service providers get listed sometimes based on other senders’ behavior.

What email deliverability actually means

Deliverability gets used loosely, so it’s worth being precise. “Delivered” in most ESP dashboards means the receiving server accepted the message and it didn’t bounce. That number is almost always high, often 98% or above, and it tells you almost nothing about whether anyone saw the email.

Inbox placement rate is the number that matters. It measures how many of your delivered emails landed in the primary inbox versus the spam folder or promotions tab. An email that lands in spam is technically “delivered.” The recipient almost certainly won’t see it.

Industry data from Return Path (now Validity) puts average inbox placement rates at around 83% globally, meaning roughly one in six emails goes to spam even from legitimate senders. For cold outreach senders using new domains, the rate is often much lower, sometimes below 50%, because the domain has no sending history and the receiving servers have no basis for trusting it.

Warmup is the process of building that trust by sending gradually increasing volumes of email that generate real engagement: opens, replies, and manual inbox placements. Providers track these signals and use them to decide how to route future mail from the same domain and IP.

The four things that determine where your email lands

Sender reputation

Every sending domain and IP has a reputation score with major providers. Google’s Postmaster Tools and Microsoft’s SNDS both let you check your current reputation directly. A domain with no history starts at neutral. Engagement signals like recipients opening, clicking, replying, and not marking as spam push the reputation up. Spam complaints, high bounce rates, and sending to inactive addresses push it down.

Reputation is IP-specific and domain-specific. If you send from a shared IP (as most small-volume senders do via ESPs like Mailgun or SendGrid), your reputation is partly determined by the behavior of other senders on the same IP. Dedicated IPs give you full control but require enough volume to warm them up properly. Below about 10,000 emails per month, a dedicated IP often has worse placement than a reputable shared one.

Authentication: SPF, DKIM, and DMARC

SPF (Sender Policy Framework) is a DNS record that lists which mail servers are authorized to send email from your domain. If you send from an ESP, their servers need to be on your SPF record. DKIM (DomainKeys Identified Mail) is a cryptographic signature attached to each email that lets receivers verify the message wasn’t tampered with in transit. DMARC tells receiving servers what to do when SPF or DKIM fails: reject the message, quarantine it to spam, or do nothing.

All three work together. DMARC only protects you if at least one of SPF or DKIM passes and aligns with the From domain. A DMARC policy of p=none monitors but doesn’t protect. It’s a starting point, not a finished configuration. Moving to p=quarantine or p=reject tells providers to actively filter or block unauthenticated mail claiming to be from your domain.

Content and engagement

Content filters look for signals that correlate with spam. These include subject lines with excessive punctuation or all-caps words, body text with a high ratio of links to words, images that make up most of the email with little readable text, and specific phrases that appear frequently in spam campaigns. The list of flagged phrases changes over time as filters update.

Engagement history matters more than content for most senders. A domain with a strong positive reputation can send emails that would fail content checks and still land in the inbox. A new domain with no history will get scrutinized more heavily on content because providers have nothing else to go on.

List quality

Sending to addresses that bounce, either because they never existed or because they were abandoned, damages your sender reputation directly. Most ESPs will suspend accounts that exceed a 5% hard bounce rate. Spam traps are email addresses that exist only to catch senders with poor list hygiene; hitting one signals that you’re emailing addresses you didn’t get through proper opt-in.

For cold outreach, email verification before sending is standard practice. For newsletter senders, suppressing anyone who hasn’t opened in 90 to 180 days keeps your engagement rates up and prevents sending to addresses that may have become spam traps.

When your deliverability test results are bad

The result page shows you which provider flagged your email and which checks failed. The fix depends on the pattern.

If authentication is failing (SPF not aligned, DKIM missing, DMARC not configured), fix those first. Authentication problems override everything else. A well-written email from a clean domain will still land in spam if DKIM fails, because the provider can’t verify where the email actually came from.

If authentication passes but you’re landing in spam across all providers, the most likely cause is sender reputation. A new domain with no warmup history, or a domain that previously had high complaint rates, will get filtered regardless of content quality. The fix is warmup: sending lower volumes through real engagement over several weeks before scaling to campaign volume.

If you’re landing in spam on Gmail but not Outlook, Google’s specific reputation signals are the issue. Gmail tracks whether recipients in your target audience have previously opened or replied to mail from your domain. If they haven’t, because the domain is new or because your list has low engagement, Gmail treats the email with less trust. Warming up specifically against Gmail addresses, and cleaning your list to focus on engaged recipients, addresses this.

If content score is the problem, the tool flags the specific issues: which phrases, which structural problems. Rewriting the subject line, reducing link count, and fixing HTML formatting are usually enough to move the score significantly. Run the test again after making changes.

Spam test vs deliverability test: which one do you need

A spam test (like the paste-content checker) reads your subject line and body and scores them against content filters. It runs in seconds and doesn’t require you to actually send anything. It’s useful for catching obvious content problems before you send.

A deliverability test sends a real email to real seed inboxes and reports actual placement. It takes 10 to 15 minutes but tells you things a content check can’t: how providers are treating your specific sending domain and IP, whether your authentication is working end-to-end, and whether you have a reputation problem that content changes won’t fix.

If you’re about to send a campaign and want a quick content sanity check, use the spam test. If you’re seeing low open rates and want to know whether emails are actually reaching the inbox, run this test. If you’re setting up a new domain for cold outreach, run this test before you send to your real list. It will tell you whether you need more warmup time before going at volume.

Fix deliverability at the source

A test shows you the problem. Warmup fixes it. Warmup Inbox runs automatic warmup on your sending domain using a network of real inboxes, sending, opening, and replying to your emails to build the engagement signals that providers use to score your reputation. Most senders see measurable improvement in placement rates within two to three weeks.