Bounce rate
Definition
Bounce rate is the proportion of sent messages that fail to deliver, and it should be kept below 5% — above 10%, sending accounts are commonly suspended.
Thresholds
| Healthy | under 5% |
|---|---|
| Warning | 5–10% |
| Critical | above 10% |
Why it matters
High bounce rate is almost always a list-hygiene problem: purchased lists, stale records, or a missing suppression sync between tools.
Amazon SES reviews accounts whose bounce rate crosses 5% and may suspend sending above 10%.