Email bounce rate
In short
Email bounce rate is the percentage of emails sent that the recipient server rejects and returns as undelivered. It is bounced emails divided by total emails sent, multiplied by 100.
It is one of the clearest signs of list quality. A high bounce rate tells mailbox providers you send to addresses you have not checked, which hurts your sender reputation.
Hard bounces vs. soft bounces
Hard bounces
Permanent failures: the address does not exist, the domain is invalid, or the server blocked you. Remove these addresses at once and never resend.
Soft bounces
Temporary failures such as a full inbox or a server outage. Retry a limited number of times, then suppress the address if it keeps failing.
How to calculate it
Say a team sends 1,000 emails and 30 bounce. The bounce rate is 3%. Track hard and soft bounces separately, since hard bounces do the most reputation damage.
Email bounce rate is a general term covering all sending. Bounce rate on its own can also mean website visitors who leave after one page, so specify email.
What causes bounces
- Outdated data: People change jobs and addresses are deactivated.
- Typos and guessed addresses: Pattern-guessed emails often fail.
- Catch-all domains: Servers that accept everything can hide invalid addresses until later.
- Blocked sending: Poor reputation or missing authentication can cause rejections.
How to lower it
- Verify before sending: Run lists through email verification and handle catch-all addresses with care.
- Use fresh data: Re-verify contacts older than a few months.
- Suppress bounced addresses: Keep a suppression list across all tools.
- Ramp new domains slowly: Start with small batches to catch problems early.
- Monitor by campaign: A sudden jump points to a bad list or technical fault.
Common mistakes
- Resending to hard bounces: This repeats the damage each time.
- Ignoring soft bounces: Repeated soft bounces often become permanent problems.
- Judging only the average: Check each list source separately; one bad source can hide behind good ones.
Email bounce rate FAQs
What is email bounce rate?
Email bounce rate is the percentage of emails you send that are not delivered because the receiving server rejects them. It is calculated by dividing bounced emails by total emails sent and multiplying by 100.
What is a good email bounce rate for cold outreach?
Lower is better, and most senders aim to keep bounces as close to zero as practical. Treat any rising trend as a warning. Check hard bounces first, verify your lists, and pause campaigns if the rate climbs suddenly.
What is the difference between hard and soft email bounces?
A hard bounce is a permanent failure, such as a nonexistent address, and should be removed immediately. A soft bounce is temporary, such as a full inbox or server issue, and can be retried a limited number of times.
How do you reduce your email bounce rate?
Verify addresses before sending, refresh older contact data, remove hard bounces right away, handle catch-all domains carefully, and warm up new sending domains gradually. Monitor bounce rate per campaign and per list source.
