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 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.
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.