A good email deliverability rate is 95% inbox placement or higher: 95 of every 100 messages reach the inbox rather than the spam folder or a rejection. It is not the same as delivery rate, which only counts messages the receiving server accepted. A campaign can show 98% delivery and 80% inbox placement, and the second number is the one that decides whether anyone reads it.
Delivery rate counts the messages a receiving server accepted: sent minus bounced. Inbox placement counts the messages that reached the inbox rather than the spam folder. A message can be accepted, pass authentication and still land in spam, so a delivery rate near 100% says nothing about whether the campaign worked.
Deliverability rate, as most senders mean it, is inbox placement. When a dashboard reports 99% delivered, it is usually reporting the first number. Ask which one is being measured before you accept that a campaign is healthy.
| Metric | Good | Watch | Fix before the next send |
|---|---|---|---|
| Inbox placement (not spam) | 95% or higher | 90 to 95% | Below 90% |
| Bounce rate | Under 2% | 2 to 5% | Above 5% |
| Spam complaint rate | Under 0.1% | 0.1 to 0.3% | Above 0.3% |
Two thresholds carry most of the weight: 2% is the working bounce limit most sending platforms enforce, and 0.3% is the complaint level Google and Microsoft publish. Your own provider may act sooner, so read its sending policy as well as these bands.
Deliverability is decided upstream of the send. Across the 7.93 million addresses BounceZero verified between April and October 2026, the share that fails or cannot be confirmed is large enough to break the thresholds above on its own.
An unverified business list does not start at a 2% bounce rate. It starts wherever its address quality starts, which is usually far higher.
| Segment | Addresses | Invalid | Catch-all | Unknown | Confirmed valid |
|---|---|---|---|---|---|
| Non-freemail (business and ISP) | 6,514,884 | 14.5% | 2.3% | 27.0% | 32.6% |
| Freemail on B2B lists | 1,415,154 | 17.6% | 1.1% | 2.1% | 74.0% |
| Business domains only | 1,269,919 | 22.9% | 9.4% | 22.5% | 40.3% |
BounceZero corpus, April to October 2026. The remainder of each row to 100% is risky and role results. Unknown means verification could not confirm the mailbox and is never counted as invalid; BounceZero refunds unknowns. Per-provider and per-TLD cuts: lead list quality benchmarks.
Take an illustrative send of 100,000 messages. The receiving server accepts 98,000, so the delivery rate is 98%. Of those accepted messages, 78,000 reach the inbox and 20,000 go to spam. Inbox placement is 80%, which is a failing number, while the delivery metric still looks healthy.
This is why open rates and delivery rates cannot diagnose a deliverability problem. Only placement data from the mailbox providers, or seed testing, shows where the accepted messages actually landed.
Invalid and unconfirmed addresses produce bounces, and bounces damage reputation before content ever matters. Verify before every send.
SPF, DKIM and DMARC decide whether the message is trusted at the door. A DMARC policy at p=none is the minimum; quarantine and reject are the goal.
Domain and IP reputation accumulate from bounces, complaints and engagement. A single high-bounce campaign can depress placement for weeks.
Subject lines, links and the text-to-image ratio matter, but they cannot rescue a sender with a 10% bounce rate.
Both give placement and reputation data by domain. Postmaster Tools requires a verified domain and a minimum volume before data appears.
Send the same message to seed inboxes across Gmail, Outlook and a secondary provider, then record where it lands.
Authentication failures show up in the rua reports before they show up in placement. Fix alignment before it costs you the inbox.
A single average hides the provider that is failing. Gmail and Outlook behave differently, and so do corporate gateways.
Across 826,000 re-verified addresses, 44.9% were still valid after 31 to 90 days and 19.2% after more than 90 days. A clean list is a dated measurement, not a permanent state.
The 2% bounce limit and the 0.3% complaint level are the thresholds most sending platforms and the largest mailbox providers use. Your own provider may enforce stricter limits, and a transactional stream may tolerate different numbers from a cold outreach stream. Measure each stream separately and use these bands to spot a problem early, not as a compliance certificate.
The four pillars, the playbook and the fixes
25 steps in the order that finds failures first
Invalid, catch-all and provider cuts from measured data
Placement and reputation by provider
Invalid and unknown rates by provider and TLD
Why a clean list goes stale in weeks
A good deliverability rate is 95% inbox placement or higher, meaning 95 of every 100 messages reach the inbox rather than spam or a rejection. Delivery rate is a different metric: it only counts messages the receiving server accepted, which can be near 100% even when placement is poor.
No. Delivery rate is the share of messages the receiving server accepted. Deliverability rate, as most senders use the term, is the share that reached the inbox. A message can be accepted and still filtered to spam, so the two numbers can differ by 20 points or more.
Under 2% is the working limit most sending platforms enforce. Between 2% and 5% is a warning zone, and above 5% most providers throttle or suspend sending. Across the BounceZero corpus, business-domain lists ran 22.9% invalid, which is why verification before sending matters more than any content change.
Under 0.1% is healthy. The level Google and Microsoft publish as the ceiling is 0.3%, and a sustained rate above that puts the sending domain at risk. Complaints come from recipients marking mail as spam, not from bounces, so the fix is usually targeting and frequency rather than list cleaning.
Verify and clean the list first, then authenticate the domain with SPF, DKIM and DMARC, then warm the sending infrastructure and send to engaged segments first. Content changes come last, because a sender with a 10% bounce rate cannot be rescued by a better subject line.
Upload the list and get valid, invalid, catch-all, unknown and role per row, then send to the confirmed addresses first. 100 free checks a month, unknowns refunded.
Ayoub built BounceZero's 5-stage validation pipeline, its dedicated sending infrastructure, and the high-availability database behind every verification. Previously built high-volume email delivery systems. Trained at 1337 Benguerir (École 42 network, 2019). Open-source: bgp_analyzer.
Provider behaviour, DNS setup, warm-up, and inbox placement
How mail routing works and why MX lookups matter for verification
Pristine vs recycled traps, how they wreck reputation, and how to avoid them
The five causes and how to stop each
Sender causes you can fix
SPF, DKIM, DMARC, reputation, and inbox placement
Authentication, list hygiene, IP warmup, ISP monitoring
Continue through related topics