288 permanent-class events
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BOUNCES / DENOMINATORS / SEGMENTS / UNCERTAINTYCalculate the rate.
Calculate the rate.
Find the source.
Separate hard, soft, and unclassified failures, preserve the attempted-recipient denominator, and see which stream contributes the problem.
- Weighted segments
- Editable thresholds
- Local calculation
TOTAL BOUNCE RATE / HOUSE CEILING
Inside both editable house ceilings.
Total ceiling 1.00% · hard ceiling 0.30% · 95% descriptive interval 0.37%–0.42%.
0.40%1,005 / 252,000attempted recipients
Accepted by the next hop is not delivered to the inbox.
This calculator describes failure events reported against attempted recipients. It does not measure inbox placement, reads, suppression correctness, or final user visibility.
652 transient-class events
65 events need mapping
99.6% of attempts; not inbox evidence
RATE PRECISION
Wilson interval around the observed proportion.
0.37%0.40% observed0.42%
This 95% interval describes binomial sampling precision under an independence model. Delivery events can cluster by domain, campaign, or outage, so it is not a forecast or a substitute for segment analysis.
FAILURE MIX
Keep severity separate before taking action.
Permanent-class failures need cause-aware suppression or correction.
Transient-class outcomes need bounded retry and escalation policy.
Preserve raw replies and improve event mapping before deciding.
SEGMENT CONTRIBUTION
Weighted totals reveal where the aggregate came from.
SEGMENTATTEMPTEDBOUNCEDRATESHARE OF BOUNCES
Product onboarding180 hard · 320 soft · 40 unknown
125,0005400.43%53.7%
Weekly newsletter90 hard · 260 soft · 20 unknown
85,0003700.44%36.8%
Account alerts18 hard · 72 soft · 5 unknown
42,000950.23%9.5%
COMPARISON + NEXT SEND
Translate rates into a house decision.
-11.4% relative change from 0.45%.
Projected bounces if the observed rate repeats across 300,000 attempts.
Maximum whole-event count at the editable 1.00% ceiling.
Difference between projection and house ceiling; zero when already inside.
DATA + OPERATIONS REVIEW
No house-rule breach found.
Transient-class events dominate the mix
Check receiver concentration, deferrals that became terminal, retry duration, routing, capacity, and time-correlated incidents.
Observed rates are inside the supplied house rules
Continue monitoring counts, cause mix, segment contribution, and comparable history; a low aggregate does not prove every segment is healthy.
Thresholds are operator inputs
The calculator does not label one percentage as universally safe across providers, streams, acquisition paths, or account policies.
DELIVERY HANDOFF
Export exact counts, formulas, intervals, thresholds, segment contribution, and findings.
THE DENOMINATOR
Bounce rate is failures divided by attempted recipients.
The tool uses attempted recipient deliveries as the denominator. It does not divide by accepted recipients, opens, contacts, or unique campaigns. Counts must refer to the same time window, message scope, and event-deduplication policy.
BOUNCE RATEhard + soft + unclassified bounces÷attempted recipients×100
RFC 3463 CLASSES
First digits describe success, transient failure, and permanent failure.
Enhanced status codes beginning with 4 describe persistent transient failure, while codes beginning with 5 describe permanent failure. Provider labels such as “soft” and “hard” are operational mappings, so preserve the enhanced code and raw SMTP response alongside the category.
2.x.xSuccess-class statusNot a bounce
4.x.xPersistent transient failureSoft category
5.x.xPermanent failureHard category
UnknownProvider mapping incompletePreserve evidence
AGGREGATES HIDE CAUSES
Segment by the dimension that can change the decision.
A global rate can look stable while one receiver, acquisition cohort, sending stream, domain, or provider is failing. Weighted aggregation preserves volume: a small high-rate segment can be important without being allowed to dominate the total purely because its percentage is large.
CAUSE BEFORE ACTION
- 01Verify accounting
Align attempted recipients and terminal bounce events to the same time window, retry policy, and deduplication key.
- 02Preserve diagnostics
Keep SMTP reply, enhanced status code, remote host, provider, timestamp, and message/recipient identifiers.
- 03Segment
Compare streams, receivers, cohorts, domains, campaigns, and infrastructure changes.
- 04Suppress precisely
Permanent invalid-recipient evidence and temporary infrastructure failure should not share one automatic action.
- 05Monitor the next window
Confirm the rate and cause mix respond after the operational change.
COMMON QUESTIONS
What denominator should bounce rate use?+
Attempted recipient deliveries in the same reporting scope as the bounce events.
Is accepted mail delivered to the inbox?+
No. SMTP acceptance is not evidence of inbox placement or user visibility.
Should every 5xx response suppress an address forever?+
No. Preserve the code and context. A permanent policy rejection can describe the sender or message rather than an invalid recipient mailbox.
What is a good bounce rate?+
Use comparable history, stream purpose, acquisition path, provider rules, and your own risk tolerance. The calculator uses editable house ceilings instead of a universal benchmark.
Why include an unclassified category?+
Forcing ambiguous events into hard or soft categories hides mapping gaps and can trigger the wrong retry or suppression action.
PRIMARY REFERENCES