Sender reputation
Sender reputation is the running record a mailbox provider keeps about a sending domain or address, built from how recipients and receiving systems treated its past mail.
Read more4. Deliverability
What is bounce rate?
Bounce rate is the portion of the emails you sent that came back undelivered. A hard bounce is permanent, because the address does not exist or the domain is wrong; a soft bounce is a temporary failure such as a full inbox.
The formula
Bounce rate
bounce rate = bounced / sent x 100
The parts
- BouncedMessages the receiving system refused or could not deliver. Count hard and soft bounces and keep an eye on each.
- SentEvery message your sending system handed off, whether or not it arrived. It is the base, so it includes the bounced ones.
- Hard and softHard bounces point to bad addresses and should be removed at once. Soft bounces may clear on a retry, but repeated ones deserve removal too.
- Why providers careMail to addresses that do not exist looks like a sender with a poor list. Google advises reducing volume when messages start bouncing, then increasing slowly again.
One send at Fernbank Payroll
Fernbank Payroll is an invented company that sent a first sequence step to a freshly verified list.
By hand
- Sent: 2,400 messages. Bounced: 36.
- 36 / 2,400 x 100 = 1.5%.
- Fernbank removes the 36 bounced addresses, checks which list source they came from and verifies the rest again before the next step.
Where the 2,400 sent messages went.
How to apply it
- Verify every address before it enters a sequence, and again if the list is old.
- Remove hard bounces immediately and drop addresses that soft bounce repeatedly.
- Compute bounce rate per sequence step and per list source, so a bad source shows up fast.
- If bounces climb, lower volume until they settle, then raise it again slowly.
Mistakes to avoid
- Counting only hard bounces and ignoring repeated soft ones.
- Dividing bounced by delivered instead of by sent, which shrinks the rate.
- Re-sending to addresses that already bounced.
Related terms
Domain warm-up
Domain warm-up is the practice of raising how much a new sending domain and mailbox send per day in small steps, so mailbox providers see steady, wanted mail before they see volume.
Read moreReply rate
Reply rate is the portion of delivered emails answered by the recipient.
Read moreQuestions
- What is a good bounce rate?
- Lower is better and there is no single published line. Google and Yahoo both advise removing invalid recipients promptly, and Google advises cutting volume when messages start bouncing.
- Are hard and soft bounces counted together?
- The formula counts all bounced messages. Track the two kinds separately as well, because they call for different actions.
- Does a bounce hurt my reputation?
- Repeated bounces suggest a poor list, and providers take that into account. Yahoo lists monitoring hard and soft bounces as part of keeping a clean list.
Sources
- Google: Email sender guidelines: https://support.google.com/a/answer/81126, read 2026-10-19
- Yahoo: Sender best practices: https://senders.yahooinc.com/best-practices/, read 2026-10-19
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