/ Glossary — Metrics
What is deliverability rate?
The share of your mail that actually reaches the inbox — not to be confused with delivery rate, which only means a message wasn't bounced. The gap between them is where deliverability lives.
/ Definition
Deliverability rate is the percentage of your sent email that actually reaches recipients' inboxes. It's easy to confuse with delivery rate, but they measure very different things — and the difference is the single most important distinction in understanding email performance.
Delivery rate counts messages the receiving server accepted rather than bounced, which says nothing about where they landed. A message routed straight to the spam folder still counts as delivered. Deliverability rate — sometimes called inbox placement rate — counts only the mail that reached the inbox, the outcome that actually matters. You can have a 99% delivery rate and a poor deliverability rate at the same time.
/ In practice
Delivery rate vs deliverability rate
Delivery rate is the share of mail that wasn't rejected or bounced — the receiving server accepted it. It's a low bar, because acceptance says nothing about placement: spam-foldered mail is delivered mail. This is why a high delivery rate can be dangerously reassuring. Deliverability rate measures the outcome that matters: did the message reach the inbox where the recipient will see it? The two can diverge sharply, and a sender watching only delivery rate can believe everything is fine while a growing share of their mail quietly lands in spam.
Why the distinction matters
Most basic sending reports show delivery rate, because it's easy to measure — the server's acceptance is right there in the SMTP response. Inbox placement is harder to measure, requiring seed lists or panel data, which is why many senders never see it and assume their high delivery rate means success. Closing that visibility gap is a core part of deliverability monitoring, and it's where reputation work pays off: the levers that move deliverability rate are authentication, reputation, and list quality, not anything that shows up in a delivery-rate report.
/ Why the confusion is costly
The false comfort of delivery rate
The gap between delivery rate and deliverability rate isn't academic — it actively misleads senders. A platform reporting 99% delivery rate gives every impression of success, and a sender with no view into actual placement will reasonably conclude their email is working. Meanwhile a growing share of that delivered mail may be landing in spam, invisible to the report, quietly eroding the results the sender thinks are fine. This false comfort is one of the most common ways a deliverability problem goes unnoticed until it's severe, because the dashboard everyone watches shows green while the inbox tells a different story.
Closing the gap
Closing the gap means measuring inbox placement directly rather than inferring success from delivery rate, and then working the levers that actually move it: authentication, reputation, engagement, and list quality. None of those show up in a delivery-rate report, which is precisely why a high delivery rate offers no assurance about them. The senders who consistently reach the inbox are the ones who stopped trusting delivery rate as a success metric and started measuring where their mail truly lands, treating the difference between accepted and placed as the core of deliverability monitoring. That shift in what they measure is, in the end, the whole difference between hoping mail arrives and knowing it does.
/ Related terms
A high delivery rate can hide a low deliverability rate. We measure the real one.
We track actual inbox placement, not just server acceptance, so you know where your mail really lands. Bring us your sending and we'll show you the number that matters.
Book infrastructure reviewRelated capabilities