Why Your Bounce Rate Matters More Than Ever
Bounce rate is one of the first numbers mailbox providers look at. See what is healthy, what drives it up and how to bring it down.
Bounce rate is the share of messages that could not be delivered. It looks like a housekeeping metric, but providers use it to judge whether you know your audience.
What is a healthy rate
A common rule of thumb is a hard bounce rate below 2% per campaign. Anything above 5% is a warning sign, and above that you risk throttling or blocks.
What pushes it up
- Old lists that were never cleaned
- Typos and fake addresses from sign-up forms
- Purchased or scraped lists
- Imports from events and partners
Why it matters now
With stricter provider rules, a bounce spike is no longer a minor nuisance. It can lower your reputation for every message you send afterwards, including transactional mail.
How to bring it down
- Verify the list with an email checker or the bulk verifier.
- Remove hard bounces after every send.
- Add real-time checks to sign-up forms.
- Re-check inactive contacts before big campaigns.
Measure it
Compare the bounce rate of the last three campaigns. A downward trend after cleaning is the clearest proof the effort paid off.
How to calculate it correctly
Bounce rate is hard bounces divided by messages sent, per campaign. Do not mix in soft bounces, which are temporary, and do not average across a year: a bad campaign last spring hides in the average and then repeats.
A short example: you send 40,000 messages and 1,200 hard bounce. That is 3%, above the 2% that most guidance treats as the line to stay under. A cleaning pass that removes 900 of those addresses would bring the next send to about 0.75% on the same list size.
Where bounces usually come from
- Old contacts that have not been mailed for months.
- Typos entered at sign-up with no check.
- Imported or purchased data with unknown quality.
- A source that changed, for example a new form or event sheet.
Look at which source a bounced address came from. Fixing the source is worth more than removing the individual addresses.
A simple response plan
- Under 1%: healthy. Keep verifying new sign-ups.
- 1% to 2%: watch. Clean before the next large send.
- Above 2%: stop and verify the whole list before sending again.
Tools
Use the bulk verifier before a campaign and the email checker at sign-up, so the number never gets high in the first place.
