Delivery rate is the percentage of messages a receiving server accepted. Inbox placement rate is the percentage that landed in the inbox rather than the spam folder.
They are wildly different numbers, and almost every sender watches the first while believing it tells them the second.
Why your platform reports the wrong one
When your platform hands a message to Gmail and Gmail accepts it, that is a delivery. Whether Gmail then files it in the inbox, the Promotions tab or the spam folder happens afterwards, inside Gmail, and is never reported back.
So a 99.2% delivery rate means 99.2% of your messages were accepted. It says nothing about where they went. A campaign can be 100% delivered and 40% in spam, and every dashboard will show a healthy green number.
This is the single most misunderstood thing in email marketing, and it is why senders with excellent-looking statistics sometimes have a programme that has quietly stopped working.
Measuring what actually happens
Seed lists. Send to a set of real accounts you control across Gmail, Outlook.com, Yahoo, Apple and a few others, then check where each landed. Free, manual, and a small sample — but it is a direct observation rather than an inference, and running one before each major campaign catches problems early.
Commercial seed list services do this at scale with hundreds of accounts and report placement by provider. They are worth the cost if email is a significant channel, with the caveat that seed accounts do not behave like real subscribers — they never open anything — so the results are an approximation.
Google Postmaster Tools. The best free signal available. It reports your domain reputation, spam complaint rate, authentication results and delivery errors as Google sees them, aggregated over your actual sends. It only covers Gmail, which for most consumer lists is the majority of the audience. Set it up before you need it, since it reports on trailing periods. See Postmaster Tools guide.
Microsoft SNDS. The equivalent for Outlook.com and Hotmail, based on sending IP rather than domain, so it is most useful if you have a dedicated IP.
Your own engagement data, read carefully. A sudden drop in open rate at one provider while others hold steady is a placement problem at that provider. Segmenting your open rates by recipient domain is a free early warning system, and almost nobody does it.
Diagnosing a placement problem
One provider only. Gmail fine, Outlook bad. Usually IP reputation or an authentication detail that provider is stricter about. Check SNDS.
All providers at once. Usually the domain or the content. Check for a blocklist listing, then check whether anything changed — a new link domain, a new sending IP, a sudden volume increase.
Gradual decline over months. Almost always engagement decay. Your list is ageing, a growing share never open, and providers are inferring that people do not want your mail. The fix is list cleaning and engagement-based suppression, not better subject lines.
Sudden drop after one campaign. Look at that campaign. A spike in spam complaints from a badly targeted send can move your reputation within days.
The things that actually determine placement
In rough order of weight:
- Recipient engagement. Opens, clicks, replies, moving your mail out of spam. This is the dominant signal and everything else is secondary.
- Spam complaints. Enforced from as low as 0.3% by Google and Yahoo.
- Authentication. SPF, DKIM and DMARC, aligned. A hard requirement rather than an advantage.
- Sender reputation of your domain and IP, accumulated over time.
- List hygiene. Bounce rates, spam traps, unknown users.
- Sending patterns. Sudden volume changes look like compromise.
- Content. Real but far less important than the folklore suggests. Link domain reputation matters more than words.
Note that content is seventh. Most senders who suspect a deliverability problem start by rewriting their emails, which is the least effective available intervention.
Improving it
Suppress unengaged subscribers. Warm new domains and IPs gradually — see domain warming. Authenticate properly, which our SPF DKIM DMARC generator will handle. Make unsubscribing easy so people do that instead of complaining. Keep volume steady rather than spiky. Send email people asked for.
Our deliverability audit checks the technical half in one pass; the engagement half is a list decision rather than a configuration one.
Frequently asked questions
What is the difference between delivery rate and inbox placement rate?
Delivery rate is the share of messages the receiving server accepted. Inbox placement is the share that reached the inbox rather than spam. Your platform can measure the first and cannot measure the second, because the filing decision happens inside the mailbox provider and is never reported back.
What is a good inbox placement rate?
Above 95% is healthy, 85–95% needs attention, and below 85% means a substantial share of your list never sees your email. Since most platforms cannot report this, you need seed testing or Postmaster Tools to know.
Why is my delivery rate 99% but my open rate falling?
Because delivery and placement are different. The messages are being accepted and filed into spam. Falling opens with a stable delivery rate is the classic signature of a placement problem.
Can I check inbox placement for free?
Partly. Google Postmaster Tools gives you domain reputation and complaint rate for Gmail at no cost, and a small self-made seed list of accounts you control gives you direct observation across providers. Commercial seed services cover more providers at scale.
