How to Test Email Deliverability Before You Send

Before you send a broadcast to 20,000 contacts, you want to know one thing: will it land in the inbox? An email deliverability test answers that before the send, not after, when it is too late to fix. This guide shows you exactly how to run one, which tools check what, how to read the result, and why a 10 out of 10 spam score still does not promise you the inbox.

The confusing part is that "test email deliverability" means three different checks that people lump together: a spam-score test, an inbox-placement test, and an authentication and reputation check. Each answers a different question, and you want all three before a real campaign. We will walk through each, then give you a comparison table and a way to read your results.

Key takeaways

• A spam-score test grades whether a specific email is configured cleanly. An inbox-placement test shows where it actually lands. They are not the same and you want both.
• Mail-Tester scores a message out of 10 by running it through SpamAssassin plus SPF, DKIM, DMARC, content, and blacklist checks. It is the fastest pre-send sanity check.
• Inbox-placement tools like GlockApps and EasyDMARC send to a seed list of real inboxes and report inbox versus spam versus tab across Gmail, Outlook, and Yahoo.
• A perfect score does not guarantee the inbox. Placement also depends on your sender reputation, engagement, and domain age, which a one-off score cannot see.
• The test simulators skip: sending the real email to your own test recipients and reading the true open rate before the broadcast.

The three tests, and which question each one answers

Deliverability testing sounds like one task. It is really three, and mixing them up is why people get conflicting results.

A spam-score test takes one specific email and grades how clean it is: are your authentication records passing, does the content trip spam filters, is the image-to-text ratio sane, are there broken links. It answers "is this message configured correctly." Mail-Tester and MailGenius are the common free ones.

An inbox-placement test sends your email to a seed list of real inboxes the tool controls, then reports where it landed, inbox, spam, or a Gmail tab, broken down by provider. It answers "where does this actually go." GlockApps and EasyDMARC do this.

An authentication and reputation check looks at your domain and sending IP independent of any one message: are SPF, DKIM, and DMARC published and aligned, is your IP on a blacklist, what is your sender reputation. It answers "is my sending identity healthy." MxToolbox, Sender Score, and Google Postmaster Tools live here.

You need all three because they fail independently. A clean message from a blacklisted IP still lands in spam. A perfectly reputable domain sending an image-only email with three spam-trigger words still gets filtered.

How to run a spam-score test (5 minutes)

This is the quickest check and the one to run every time you change a template.

1. Go to Mail-Tester and copy the unique address it generates for you.
2. From your actual sending tool, send the real email you plan to broadcast, with your real subject line and links, to that address. Do not send a stripped-down test, send the real thing.
3. Click "Check your score." You get a score out of 10.
4. Read the per-rule breakdown, not just the number. It lists exactly what cost you points.

Per Mail-Tester's own documentation, the tool runs your message through SpamAssassin and gives you three free tests every 24 hours. Aim for 10 out of 10, but treat 8 or above as acceptable for a first pass and fix the specific items it flags rather than chasing a perfect number for its own sake.

How to run an inbox-placement test

A spam score cannot tell you that you are landing in Gmail's Promotions tab, because Promotions is not spam. For that you need a placement test.

1. Pick a placement tool such as GlockApps or EasyDMARC.
2. It gives you a list of seed addresses across Gmail, Outlook, Yahoo, and others.
3. Send your real campaign to all of them from your sending tool.
4. The tool reports the percentage that landed in inbox, spam, or a specific tab, per provider.

This is the test that reveals provider-specific problems. It is common to land in the Gmail inbox but the Outlook spam folder, or the Gmail Primary inbox for engaged contacts but Promotions for everyone else. A placement test makes that visible before your whole list sees it.

How to check authentication, blacklists, and reputation

These checks are about your sending identity, so you run them on your domain and IP, not on a single email.

For authentication and blacklists, run your domain and sending IP through MxToolbox. It checks SPF, DKIM, and DMARC records and tests your IP against a large set of blacklists. If a record is missing or misaligned, fix it before anything else, our SPF, DKIM, and DMARC explainer shows the exact records to publish, and our guide to an email blacklist check covers delisting if you are listed.

For reputation over time, set up Google Postmaster Tools. Unlike the one-off tests above, Postmaster shows your spam rate and domain reputation on real Gmail traffic across days and weeks. Per Google's sender guidelines, keep your spam complaint rate below 0.10 percent and never let it reach 0.30 percent. Sender Score, a free reputation lookup from Validity, gives you a quick 0 to 100 snapshot of your IP's reputation as a complement.

The tools, compared

Here is what each common tool actually checks, so you can pick the right one for the question you have.

There is one more test the list above cannot do, and it is the one that matters most before a broadcast. Every tool here either scores a message in isolation or sends to the tool's own seed inboxes. None of them send your real campaign to your real recipients and tell you whether real humans opened it. That is a gap you can close with your own sending tool: send the actual broadcast to a small set of test recipients you control, then read the true open rate on that send before you release it to the list.

Why a 10/10 score does not guarantee the inbox

This is the single most misunderstood thing about deliverability testing, and Mail-Tester says it plainly in its own FAQ: a perfect score does not guarantee delivery, because every spam filter works differently.

A spam score measures configuration. It confirms your one email is authenticated, clean, and not tripping obvious content filters. What it cannot see is everything that lives outside that single message: your sender reputation built over weeks, how engaged your recipients are, your domain age, your complaint history, and each provider's private filtering model. You can score 10 out of 10 and still land in spam because your domain is new and unwarmed, or because your last three sends drew complaints. The score is necessary, not sufficient. Treat it as one input alongside a placement test and your reputation data, not as a green light on its own.

How to read your results and what to fix

A test is only useful if you act on it. Here is how to translate common failures into fixes.

• SPF fails or is missing. Publish or correct your SPF TXT record so it authorizes your sending service. If you use multiple services, combine them into one record.
• DKIM fails. Make sure your provider's DKIM CNAME or TXT records are published and that you are signing with the matching selector.
• DMARC shows none or fail. Publish a DMARC record starting at p=none, watch the reports, then tighten. A DMARC fail with SPF passing usually means an alignment problem, fix the From domain, not the policy.
• On a blacklist. Identify which list, fix the cause (often a compromised account or a bad list), then file the delisting request for that specific list.
• High image-to-text ratio or spam words. Add real text, cut heavy images, remove the flagged trigger phrases, and make the unsubscribe link obvious.
• Good score, bad placement. This is a reputation or engagement problem, not a content one. Pull back to your most engaged contacts and re-warm your sending.

For the full picture of how these pieces fit, from authentication through warm-up to fixing a damaged reputation, see our complete email deliverability guide and our deep dive on sender reputation.

Where Meisa fits

The tools above are how you test. When it is time to actually send, the sending tool decides how much of that test result survives contact with production. Meisa is an email platform for SaaS teams that runs on your own Amazon SES, so you own the sending IP and reputation you spent all that testing to protect. It verifies your domain with DKIM, SPF, and DMARC, and it closes the gap the simulators leave open: you can send a real broadcast to your own test recipients and read a true open rate, which separates genuine human opens from Apple MPP and corporate-scanner opens, before the campaign goes to your list.

To be fair about it, if all you need is a standalone one-off spam score, Mail-Tester is free and does that job well, and you do not need a platform for it. Meisa earns its place when you are running real lifecycle email and broadcasts and want the pre-send test, the sending, and honest post-send analytics in one place you control. See the best email tools for SaaS for how it compares to the alternatives.

Frequently asked questions

How do I test if my email is going to spam?

Run two tests. First, a spam-score test: send your real email to a Mail-Tester address and read the score and the per-rule breakdown. Second, an inbox-placement test with GlockApps or EasyDMARC, which sends to real seed inboxes and reports whether you land in inbox, spam, or a Gmail tab per provider. The placement test is the one that actually confirms spam versus inbox.

How do I check my email deliverability for free?

Several tools have free tiers. Mail-Tester gives you three free spam-score tests per 24 hours, MxToolbox offers free one-off blacklist and authentication lookups, EasyDMARC has a free inbox-placement tier with daily caps, and Google Postmaster Tools is free for ongoing Gmail monitoring once you verify your domain in DNS.

What is a good Mail-Tester score?

Aim for 10 out of 10. A score of 8 or above is usually acceptable for a first pass. More important than the number is the per-rule breakdown, fix the specific items it flags, especially any SPF, DKIM, or DMARC failures. Remember that a perfect score confirms configuration, not that you will reach the inbox.

Can I run an email deliverability test with MxToolbox?

Yes. MxToolbox is best for the authentication and blacklist side of testing. You send a message to its deliverability address or run its lookups to check SPF, DKIM, and DMARC, DNS and MX configuration, and whether your IP or domain is on a blacklist. For actual inbox placement across providers, pair it with a placement tool like GlockApps or EasyDMARC.

How often should I test deliverability?

Run a quick spam-score test every time you change a template or sending setup. Run an inbox-placement test before any large or important broadcast. And monitor continuously in production with Google Postmaster Tools so you catch a reputation slide before it turns into a spam-folder problem.