Getting an email bounce rate back under control
Your email service provider has flagged the account, or a campaign report shows a bounce rate north of 3% and somebody upstairs has noticed. This page is about email delivery failures, not the web analytics metric that shares the name.
Your window is short. Amazon SES puts an account under review at 5% and can pause sending at 10%. Mailchimp and most others act sooner and with less warning, and the suspension applies to the account rather than the campaign.
The order the work happens in
Separate hard from soft in the last report
A hard bounce means the mailbox doesn't exist. A soft bounce means a full inbox, or a server having a bad day. Only the first group needs removing, and mixing them is how you delete addresses that were fine.
Suppress every hard bounce on first failure
Some platforms retry a hard bounce several times before giving up, and every retry counts against you. One failure with a 550 is enough evidence.
Verify the segment you are about to send to
Not your whole database. The addresses going out in the next campaign are the ones that can hurt you this week, and checking those first gets the number down before the next send rather than the next quarter.
Split the send by age
Addresses you collected in the last ninety days barely bounce. Addresses from three years ago carry most of the risk. Sending to them in one batch averages the risk across a campaign the provider judges as a whole.
Fix the collection point
A list that produces a high bounce rate usually has a form with no validation behind it. Clean the list without fixing the form and you'll be doing this again in six months.
What each result means here
The same four results and their flags, read against this job. A catch-all worth keeping in one situation is one to exclude in another.
| Result | What to do with it |
|---|---|
| Valid | Send. This is the group whose bounce rate you are trying to measure honestly. |
| Invalid | Remove before the send. These are the addresses producing the number. |
| Catch-all | Send in a later batch, on its own, so you can see what it does to the rate without it contaminating the main campaign. |
| Unknown | Hold back while the account is under scrutiny. Once the rate is healthy, test a sample of them. |
| Role flag | Keep, unless the complaints are coming from role addresses, which happens on cold lists. |
| Disposable flag | Remove. These bounce as the provider recycles them and they never engage. |
How you know it is finished
Two consecutive campaigns land under 2% hard bounces without you having culled the list further between them, which shows the improvement came from the data rather than from a single careful send.
What this does not fix
Checking one campaign segment of 20,000 addresses rather than a whole database is the cheap version of this job: $25 buys 10,000 credits and unknown results are not billed, so a segment heavy in domains that won't answer costs less than the count suggests.
Questions people ask
What is an acceptable email bounce rate?
Under 2% is the working figure for a healthy list, and most providers start paying attention above that. Amazon SES states 5% as a review threshold and 10% as a pause threshold, which are the outer limits rather than targets.
Do soft bounces count against me?
Less, but not zero. Repeated soft bounces to the same address eventually read as a hard failure, which is why platforms convert them after several attempts.
Will verification alone fix the problem?
It fixes the part caused by dead addresses. If your problem is a purchased list, broken authentication or a sending pattern the providers dislike, your rate will stay high on a perfectly clean file.
Try it on the file in front of you
100 free checks a month, no card. Addresses we could not get an answer on come back labeled as unknown, and those are not billed.