Inbox placement rate
Inbox placement rate (IPR) is the percentage of delivered emails that actually land in the primary inbox rather than the spam/junk folder or a tab like Promotions. Unlike 'delivered' (which only means accepted by the server), IPR measures whether a human is likely to see the message.
How it works
Seed-list and panel-based placement tests send to known mailboxes across providers and report where each message landed. The result reflects authentication, reputation, content and engagement combined.
Why it matters
'Delivered' can be 99% while inbox placement is 40%. IPR is the metric that actually predicts opens and replies, which is why deliverability programs optimize it directly.
How do you calculate placement from a seed test?
Divide the seeds that reached the primary inbox by all seeds you sent to, then break the result down by provider. In a hypothetical test to 40 seed mailboxes, 26 land in the inbox, 9 in spam, 3 in a Promotions tab and 2 never arrive. Placement is 26 out of 40, or 65%. Report the missing two separately, because a message that never arrives is a delivery or blocking problem, not a filtering one.
The per-provider split is where the action is. If 13 of 15 Gmail seeds reach the inbox but only 6 of 15 Microsoft seeds do, the account-wide 65% hides a problem specific to one receiver, and fixing copy for everyone would be the wrong response.
How far can you trust a seed-list result?
Treat it as a trend line, not a verdict. Seed mailboxes have never replied to you, so they see your mail the way a stranger does, while prospects who have written back may get friendlier filtering. Consumer seed accounts also miss the corporate security gateways that sit in front of many B2B inboxes, and a sample of a few dozen swings noticeably from one run to the next.
To make results comparable, keep the seed list, the sending mailbox and the message fixed and change one thing between runs. Our guide on how to test email deliverability sets out a repeatable routine. A change smaller than a few seeds between two runs is usually noise.
Does a Promotions-tab landing count as inbox placement?
Testing tools disagree, so choose a rule and keep it. For one-to-one sales email, a Promotions landing usually signals that the message looks like marketing: HTML layout, several images, tracked links or an unsubscribe footer styled like a newsletter. A plain-text version of the same email often moves to the primary tab. Whether that is worth doing depends on whether your recipients check Promotions at all, which you can only infer from replies.
Whatever rule you pick, apply it to every run and every provider. A dashboard that counts Promotions as inbox for Gmail but as a miss in another tool's report will show movement that is only a change of definition. Our list of ways to stay out of the spam folder covers the formatting choices that decide which tab a message lands in.
What should you change first when placement is low?
Authentication, because it is quick to confirm and fix: the deliverability checker shows SPF, DKIM and DMARC status in one pass. Next, cut links and images to the minimum and remove link shorteners. Then look at the list and at daily volume per mailbox. Rewriting subject lines comes last. Autocloz runs inbox-placement tests alongside warmup and authentication monitoring, so a drop is visible before it shows up as a fall in replies. For the wider picture, see cold email deliverability.
How Autocloz handles it
Autocloz runs inbox-placement tests and pairs them with warmup, authentication monitoring and rotation, so you optimize for where mail lands — not just whether it was accepted.
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FAQ
What is the difference between delivery rate and inbox placement?
Delivery rate counts emails the receiving server accepted (inbox or spam). Inbox placement counts only those that reached the primary inbox. The gap between them is your real deliverability problem.
Related terms
Mailbox warmup is the practice of gradually increasing a new email account's sending volume while generating positive engagement (opens, replies, moving mail out of spam) so mailbox providers build trust in the sender before real campaigns ramp up.
Sender reputation is the trust score mailbox providers assign to your sending domain and IP based on how recipients react to your mail — opens, replies, spam complaints, bounces and spam-trap hits. A high reputation lands you in the inbox; a low one routes you to spam or blocks you.
Domain reputation is the trust score mailbox providers assign to your sending domain based on its authentication, sending history, engagement and complaint signals. Unlike IP reputation, it follows the domain wherever it sends, which is why it has become the dominant reputation signal as senders share pooled IPs.
IP warmup is the process of gradually increasing sending volume from a new or dormant dedicated IP address while maintaining high engagement, so mailbox providers build trust in that IP before it sends full volume. Sending large volume from a cold IP triggers throttling or spam-foldering because providers have no history to trust.
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