The acceptable bounce rate is a ceiling you manage. Treating it as a target can damage the list. Calculate total bounces against attempted sends and split the result into hard and soft bounces.1 Teams often rewrite copy when reply rate looks low.2 A scraped list, a bounce rate above 3 percent, or open-rate numbers affected by privacy software may be the actual problem.3 Check the bounce pattern before changing the message, because list quality may be at fault.
Set the threshold before you send
Set thresholds before inspecting individual addresses. Give each threshold its own action so you can pause before delivery collapses.
For cold email, keep the total bounce rate below 2 percent.4 Treat anything above 0.5 percent as an urgent list hygiene signal.5 Crossing 2 percent may lead providers to filter future email while the underlying list problem remains unresolved.6
During warmup, keep the rate under 2 percent.7 If it exceeds 3 percent, stop sending and clean the list.
Before sending, decide where you will see the total rate, hard rate, soft rate, and the domains producing failures. Decide who owns the cleanup. A bad result should trigger a pause and investigation before another batch.
Separate hard and soft bounces
Classify every failure before choosing whether to retry, suppress, or investigate it. The type shows how permanent the problem may be and how risky another send could be.
A hard bounce occurs when the receiving server explicitly says the address is invalid.8 Hard bounces are permanent and cause more sender IP damage than soft bounces.9 A soft bounce is temporary and affects a valid email address.10
Soft bounces and deferrals are treated as transient failures and may be retried, including failures caused by a full mailbox.11 A recipient server can also soft bounce after receiving too many emails during a period of time.12 Sending above the rate recommended by an Internet Service Provider can cause the same failure.13
Both types affect sender IP reputation because providers use total bounce rate when deciding where to direct email.14 Check soft bounce patterns even when the individual address may recover.
An account level suppression list adds only hard bounces.15 Use it to prevent sends to addresses that have already failed permanently. Keep retry decisions separate from suppression decisions because a temporary failure and an invalid address require different handling.
Diagnose the pattern before changing copy
Once you have the type, find where the failures cluster. Domain concentration and timing show whether to clean the list, slow the sending pattern, or investigate a provider incident.
Start by identifying the impacted Internet Service Providers and their bounce rates.16 Review the overview and the 14 day trend for each provider's hard and soft bounce rates, along with the overall hard and soft rates.17
Look for a sudden increase in hard bounces.18 Look for consistent soft bounces to specific domains.19 A broad rise across many domains points to list quality or sending behavior. A narrow rise gives you a domain or provider pattern to investigate first.
For an individual email ID, check whether delivery occurred. If it did not, record the error, bounce category, and code.20 To find a repeatable problem, pull the email IDs with the same error, category, or code across a defined period or message delivery.21
Check for an Internet Service Provider outage before deleting addresses from a domain that suddenly fails. During an outage, identify addresses incorrectly marked as bounced or quarantined for the affected domains and timeframe.22 This keeps a provider event from turning into unnecessary list loss.
Clean, then recheck
End cleanup with a measured follow-up send. Keep the same view of the data after the fix so you can see whether the failure pattern changed.
For soft bounces, monitor the soft bounce rate and reevaluate after two sends if it drops below 0.5 percent.23 If it does not drop below that level, summarize the error codes and messages from the Soft_bounced messages last 14 days dashboard report and share the summary with the regional emailing specialist.24
For hard bounces, monitor performance and the hard bounce rate over the next one sending day.25 If mail validation is complete or the hard bounce rate will not drop below 0.5 percent, summarize the errors from the Hard_bounced messages last 14 days report in the Warm-up use case and share the summary with the regional emailing specialist.26
Be deliberate when removing a hard_bounce record. An address that still does not exist will bounce on the next send and be suppressed again.27 Fix the address or leave the suppression in place when the underlying cause remains.
What not to do
- Do not remove a hard_bounce record casually. A nonexistent address will bounce again and be suppressed again.27
- Do not assume every bounce comes from an invalid address. Resource exhaustion, such as a full disk, and spam filter rejection can also cause a bounce.28
- Do not keep retrying a recipient forever. In systems that clean audiences this way, continued soft bounces can eventually be treated as hard bounces and removed.29