Glossary · Email & deliverability · Last updated October 31, 2026
Bounce rate
Bounce rate is the percentage of sent emails that were returned as undeliverable; for cold email, under 2% is a sensible target.
Also called: Email bounce rate.
Bounce rate is bounces divided by emails sent. Tools count differently: Amazon SES calculates its bounce rate from hard bounces only, while some sequencers include soft bounces, so compare like with like.
Mailbox providers like Gmail and Yahoo don't publish a bounce-rate limit. They publish a spam complaint threshold (Google: stay below 0.1% and never reach 0.3%) and expect you to stop sending to addresses that bounce. Google says to automatically unsubscribe recipients with multiple bounced messages.
Bounce thresholds come from sending tools and email services. Instantly auto-pauses a campaign above 5% once it has sent at least 200 emails. Amazon SES advises staying below 5% and may pause an account at 10%. Woodpecker's default auto-pause is 2%. A rate between 2% and 5% isn't safe; it's where reputation erodes before anything stops you.
In local lead generation, high bounce rates nearly always come from the list: pattern-guessed addresses, unverified or stale data, closed businesses, and catch-all domains mixed in with verified ones. The fix is verification shortly before sending, separate segments for catch-all addresses, and removing every hard bounce at once.
Example
A campaign to 2,000 businesses gets 62 bounces: 62 ÷ 2,000 = 3.1%. Splitting the results shows the verified segment bounced at about 1% and the catch-all segment far higher, so the catch-all batch is paused and the verified one continues.
Sources
Related terms
- Hard bounceA hard bounce is a permanent delivery failure, such as an address that doesn't exist, returned with an SMTP reply code starting with 5.
- Soft bounceA soft bounce is a temporary delivery failure, such as a full mailbox or busy server, returned with an SMTP reply code starting with 4.
- Sender reputationSender reputation is the trust mailbox providers place in your sending domain and IP, built from complaints, bounces, authentication and engagement.
- Email verificationEmail verification is checking whether an address can receive mail, using syntax, MX and SMTP tests, without sending a message to it.
- Email deliverabilityEmail deliverability is the ability of your emails to reach recipients' inboxes rather than bouncing or landing in spam.
Further reading
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