Deliverability metrics are how mailbox providers grade your sending behaviour. You can’t see the grade directly. You can see the numbers it’s built from, and those numbers tell you whether your mail is arriving before anyone opens it.
Metrics at a glance
- Inbox placement rate, above 85% is great, measured over emails sent
- Delivery rate, 98%+, over sent. Not the same thing, and this page explains why
- Spam complaint rate, below 0.1%, over delivered
- Bounce rate, at or below 1%, over sent
- Unsubscribe rate, 0.2 to 0.5%, over delivered
- Block rate, near zero, over sent
- Authentication pass rate, 100%, over sent
Opens and clicks aren’t on that list, they’re engagement metrics.
7 Email Deliverability Metrics to Track
Four of these measure whether mail arrived. Three measure how it was received. Only the first group is deliverability.
Each benchmark says what it’s measured against, because two of the seven are measured over delivered email and five over everything you sent. The same performance produces two different percentages depending on which you pick.
Each one below gets a formula, a worked example, and the threshold where it stops being a number and becomes a problem.
Inbox Placement Rate
(emails in the inbox ÷ emails sent) × 100
Worked example: 8,200 in the inbox out of 10,000 sent is 82%.
Above 85% is great. 80 to 85% is good, 75 to 80% is worth watching, and below 75% needs action.
The global average sits at about 83.1%, so a typical sender is in the good band rather than the great one.
Delivery Rate
Delivery rate counts what the receiving server accepted, wherever it ended up. Above 98% is good and below 95% is a warning.
It’s on this list because the contrast is what makes inbox placement meaningful. The arithmetic belongs to our guide to deliverability rate.
Spam Complaint Rate
(complaints ÷ emails delivered) × 100
Keep it below 0.1%. That’s the target you manage to; 0.3% is where Google begins enforcing, and you don’t want to discover the gap between the two.
Complaints need a feedback loop before you can see any of them. Most senders have never registered for one, which means their complaint rate reads as zero for the wrong reason.
Bounce Rate
(bounces ÷ emails sent) × 100
At or below 1% is healthy; above 5% is a real problem.
A hard bounce is a permanent failure, usually an address that doesn’t exist.
For eg: 50 hard bounces on 10,000 sends is 0.5%.
A soft bounce is temporary, like a full mailbox, and matters only when the same address keeps soft-bouncing.
Spam trap hits sit here too. A trap is an address that was never a real person, or was abandoned and repurposed. Hitting one says your list came from somewhere you can’t vouch for.
How to Fix Bounced Emails? (And Prevent Them) covers the cleanup.
Unsubscribe Rate
(unsubscribes ÷ emails delivered) × 100
Between 0.2 and 0.5% per campaign is normal. Sudden spikes usually point at targeting or messaging rather than frequency.
One diagnostic almost nobody publishes: if complaints exceed unsubscribes, your opt-out process is broken. People who can find the unsubscribe link use it. People who can’t press the spam button instead.
Block Rate
A block is a rejection before the message reaches any folder. It isn’t a bounce, and your platform may not separate the two.
Causes are blocklisting, poor domain reputation, or failed authentication. The benchmark is near zero. Any sustained block rate is an incident to work, not a metric to optimise.
Authentication Pass Rate
The share of your mail passing SPF, DKIM and DMARC alignment, visible in DMARC reports and almost nowhere else.
The benchmark is 100%. Anything less means some of your mail is going out unauthenticated. The cause is usually a forwarding path, or a third-party sender nobody remembered was still configured.
Email Deliverability Benchmarks
| Metric | Healthy | Watch | Act now | Measured over |
|---|---|---|---|---|
| Inbox placement rate | Above 85% | 75 to 85% | Below 75% | Emails sent |
| Delivery rate | 98%+ | 95 to 98% | Below 95% | Emails sent |
| Spam complaint rate | Below 0.05% | 0.05 to 0.1% | Above 0.1% | Emails delivered |
| Bounce rate | At or below 1% | 1 to 5% | Above 5% | Emails sent |
| Unsubscribe rate | Below 0.2% | 0.2 to 0.5% | Above 0.5% | Emails delivered |
| Block rate | 0% | Any sustained rate | Rising | Emails sent |
| Authentication pass rate | 100% | 98 to 99% | Below 98% | Emails sent |
*Figures above are drawn from published industry sources and our own sending data, not from a single measured study.
The global average inbox placement rate is about 83.1%, which lands in the good band. A single campaign tells you nothing, but 30 days tells you something.
Where Each Metric Comes From
No single dashboard reports all seven, and the two that matter most are the two nobody reports by default.
Every source below is free, and most senders have never opened three of them.
| Source | What it gives you | What it cannot |
|---|---|---|
| Your sending platform | Sent, delivered, bounces, unsubscribes | Inbox placement, block rate, folder |
| Google Postmaster Tools | Spam rate, domain reputation, authentication results | Anything outside Gmail. Folder within Gmail |
| Microsoft SNDS | IP-level complaint data and spam trap hits | Domain-level reputation, anything outside Microsoft |
| ISP feedback loops | Individual complaints | Nothing until you register for them |
| Seed-list placement test | Actual folder placement per provider | Whether real recipients engaged |
| DMARC reports | Authentication pass rate, unauthorised senders | Placement or engagement |
The gap in one sentence: your platform reports delivery, providers report reputation, and neither reports where the message landed.
Feedback loops need registering. Complaints stay invisible until you sign up with each provider, and it’s the most commonly skipped step on this list.
Check weekly during active sending, monthly otherwise, and always after a change to volume, domain or list source.
3 Things People Get Wrong About These Numbers
- My delivery rate tells me how many emails reached the inbox: It tells you how many didn’t bounce. A delivered email can be in spam, in Promotions, or silently blocked.
- A low complaint rate means I’m fine. Complaints are one input: Poor domain reputation, failed authentication or a blocklist entry will send mail to spam with a complaint rate of zero.
- Avoiding spam words fixes placement: Content is a minor factor next to reputation and engagement. A trusted sender clears content filters that a new domain doesn’t.
What to Do When a Metric Breaks
Pair the symptom with the cause. This section diagnoses; fixing is a different job.
- Placement falling, bounce rate stable → reputation or engagement
- Placement falling, bounce rate rising → list quality
- Complaints rising, unsubscribes flat → targeting, not content
- Complaints higher than unsubscribes → your opt-out process is broken
- Block rate above zero → check blocklists and authentication before anything else
- Authentication pass rate below 100% → a forwarding path or third-party sender you didn’t authorise
- Fine on Gmail, poor on Outlook → provider-specific filtering
Once you know which one it is, how to fix a falling number takes it from there.
Engagement Metrics Are Not Deliverability Metrics
Open rate, reply rate and click-through rate measure whether people acted. Deliverability measures whether the message arrived. Both matter, and confusing them is how a sender ends up optimising subject lines while a reputation problem goes unattended.
They have their own home: email engagement metrics covers them properly, including how they differ for cold outreach.
Close
Check inbox placement rate weekly. Everything else on this page is a leading or lagging indicator of it. The line that should trigger action is below 75%, or any sustained block rate. Measuring tells you a problem exists. Fixing it is separate work.
Frequently Asked Questions
1. What Are the Most Important Email Deliverability Metrics?
Inbox placement rate, spam complaint rate, bounce rate and block rate. Those four measure whether your message arrived. Unsubscribe rate and authentication pass rate are close seconds.
Open and click rates measure what happened after arrival. That makes them engagement metrics, however often they appear on lists like this one.
2. What Is a Good Inbox Placement Rate?
Above 85% measured against emails sent is great, and 80 to 85% is good. Between 75 and 80% is worth watching, and below 75% signals a real problem.
3. What Is the Difference Between Delivery Rate and Inbox Placement Rate?
Delivery rate counts emails a receiving server accepted, wherever they ended up, including spam. Inbox placement rate counts only those that reached the inbox.
A campaign can show 98% delivery and inbox placement in the seventies. That is the single most common misreading of email reporting.
4. Can Deliverability Metrics Drop Even if I Follow Best Practices?
Yes. Providers change filtering rules, volume spikes register as anomalies, and a small unengaged segment can drag a whole domain down.
A trend across thirty days is worth more than any single reading. One bad send isn’t automatically a problem to fix.
5. Should I Pause Sending if My Metrics Fall?
Reduce rather than pause. Cutting volume by a quarter and holding steady lets providers reassess you. Stopping entirely removes the signals they’d reassess you on.
Fix the cause during the reduction, then ramp back gradually rather than in one step.
