An inbox placement test sends your email to a list of managed seed addresses across Gmail, Outlook, Yahoo, and other providers, then reports where each copy landed: primary inbox, a tab like Promotions, spam, or missing entirely. Tools like GlockApps run this live and return results in minutes.
An inbox placement test sends your email to a list of managed seed addresses across Gmail, Outlook, Yahoo, and other providers, then reports where each copy landed: primary inbox, a tab like Promotions, spam, or missing entirely. Tools like GlockApps run this live and return results in minutes.
It is the best pre-send signal you can get, and it is also directional, not precise. Seed inboxes have no history with your domain, and the seed-list method was built for newsletters, not one-to-one cold email. A 20% spam result from seeds nobody opens does not mean 20% of your real prospects saw spam. This post covers how the test works, how to read it, and the five things it cannot tell you.
An inbox placement test measures where an email lands across multiple mailbox providers by sending it to a controlled set of seed addresses and recording the folder each copy reaches. It reports placement as inbox, tab, spam, or missing, broken down by provider. Results are directional: seed accounts lack engagement history with the sender, so real-recipient placement can differ.
A live send to accounts you can inspect. You get a seed list from the testing tool, send your real campaign email to it from your real sending mailbox, and the tool checks each seed account and reports the folder. GlockApps covers Gmail, Yahoo, Outlook, AOL, Comcast, and dozens more.
The output is a placement breakdown: what percentage reached the inbox, what went to tabs, what went to spam, and what went missing or blocked, with a per-provider split. Gmail and Outlook are the two rows that matter most for B2B.
The seed list is a set of managed email accounts across many providers. You use it one of two ways: send a separate test campaign to the whole seed list, or distribute the seed addresses inside your real campaign so the test rides along with a live send.
For cold email, the separate test send is simpler and cleaner. Send the exact message and subject line you plan to use, from the warmed mailbox on the secondary domain you will run the campaign from. Within a few minutes the tool shows you the placement map.
Four numbers, per provider.
A clean result is 90%-plus inbox, near-zero spam, no blocked, and consistent across providers. Lopsided results, fine at Gmail but spam at Outlook, tell you which provider relationship to work on.
The two ways to use a seed list produce slightly different reads. A separate test send, where you email only the seed list, isolates the message and setup cleanly, which is what you want when diagnosing a problem or checking a new template. Distributed seeds, where seed addresses are salted into your real campaign list, show how the message performs alongside genuine recipient activity, which is closer to production but noisier.
For cold email, run the separate test send as your default. Use distributed seeds only when you suspect a specific segment or list source is dragging placement down and you want to see the seed results in that real context. Either way, keep the sending mailbox and domain constant across tests so you are comparing like with like over time.
The seed test is an early-warning system. Your ground truth is elsewhere: your live campaign's open and reply rates, and your Gmail spam rate in Google Postmaster Tools. Those reflect what real recipients and real filters did.
Use them together. Run a seed test before a big campaign to catch obvious problems, then watch the live metrics as the campaign runs. If the seed test was clean but opens crater, believe the opens. If the seed test showed spam but opens are healthy, the seed test likely overstated it. Pair this with a monthly email domain reputation check.
Weekly while a domain is warming up. Monthly once it is established. Always before a large campaign, after any change to sending configuration or content templates, and when adding a new sending domain to the fleet. More frequent testing during warm-up is worth the cost because that is the window where a small decline is still cheap to reverse. See how to improve email deliverability.
The Directional-Read Rule: a seed inbox placement test reads direction and trend, not precise reality. Act on a consistent decline across several tests, not on one number from one run.
The rule protects you from two mistakes. Overreacting to a single bad test, tearing apart a campaign because one run showed 15% spam from seed accounts that never open anything. And underreacting to a slow slide, ignoring a placement rate that has drifted from 95% to 90% to 84% across three weekly tests because no single drop looked alarming.
Plot the tests. A jagged line that averages 92% is fine. A smooth line heading down is a domain reputation problem forming, and it is far cheaper to fix at 90% than at 70%. The quotable version: "A seed test tells you which way you are heading, not exactly where you are."
Cross-check every concerning trend against your live open and reply rates before you change anything.
An inbox placement test can show your reputation slipping. What it cannot do is fix the cause, which is almost always a list carrying dead addresses and unengaged contacts that drive the bounces and complaints behind a declining placement rate.
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An inbox placement test sends your real message to seed accounts across providers and reports where it lands. Run it from your real mailbox with your real campaign email, read Gmail and Outlook first, and aim for 90%-plus primary inbox. Treat the result as directional: seeds have no engagement history with you, the method suits newsletters better than cold email, and a single bad number is a prompt, not a verdict. Watch the trend across weekly tests, cross-check against live open and reply rates, and remember that a verified list is what holds placement steady.
How does an inbox placement test work?
You send your real campaign email from your real sending mailbox to a list of managed seed addresses across Gmail, Outlook, Yahoo, and other providers. The testing tool checks each seed account and reports which folder the message reached, broken down by provider, usually within a few minutes of the send.
What is a good inbox placement rate?
Ninety percent or higher reaching the primary inbox at Gmail, Outlook, and business domains, with near-zero spam and nothing blocked. Tab placement in Promotions counts as close to a miss for cold B2B. Lopsided results, such as inbox at Gmail but spam at Outlook, point to a specific provider relationship to work on.
Is an inbox placement test accurate for cold email?
It is directional. Seed accounts have no engagement history with your domain, and the seed-list method was designed for bulk newsletters rather than one-to-one cold email. A seed test can overstate a problem, since a spam result from a seed nobody opens does not mean a real prospect saw spam. Use it for trend, not precision.
How often should I run an inbox placement test?
Weekly while a sending domain is warming up, since placement changes fastest then. Monthly once the domain is established. Always run one before a large campaign, after any change to sending configuration or email templates, and when adding a new sending domain to your fleet.
What is the difference between an inbox placement test and a spam score?
A spam score rates your content and authentication against filter rules and returns a number. An inbox placement test actually sends to real seed inboxes and reports folder placement per provider. You can have a clean spam score and still land in spam, because the score cannot see your domain reputation.
Why does my placement test look worse than my real results?
Seed accounts never engage with your mail, so engagement-weighted filters like Gmail's treat them more harshly than they treat your real, opening, replying prospects. Your true inbox rate with engaged recipients is often better than the seed test shows. Trust your live open and reply rates as the real measure.
Microsoft 365 work and school accounts can send to 10,000 recipients per rolling 24 hours, with a default of 500 recipients per message and a rate limit of 30 messages per minute. Free Outlook.com accounts get roughly 300 a day.
Never run cold outreach from the domain your product, invoices, and support email live on. That is the whole case for secondary domains.
Before you compare SMTP prices, read the acceptable use policy. Amazon SES, SendGrid, Mailgun, and Postmark all restrict or prohibit unsolicited email, and their accounts get reviewed at roughly one spam complaint per thousand emails.
A spam score checker runs your email through SpamAssassin-style rules and returns a number, plus a list of exactly which rules you triggered. A SpamAssassin score below 2.0 is safe for almost every mail server; 2.0 to 5.0 is moderate risk; above 5.0 gets the message rejected or filtered.
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