What is a good email bounce rate, and how do you calculate it?
Email bounce rate is the percentage of sent emails returned as undeliverable. Calculate it as bounced emails divided by emails sent, multiplied by 100. As a common rule of thumb, under 2% is good, 2% to 5% needs attention, and above 5% points to a list or setup problem. For cold email, many senders aim to stay under 1% to 2%.
| Bounce rate | What it usually means | What to do |
|---|---|---|
| Under 1% | Clean, recently verified list | Keep verifying new contacts before they enter a campaign |
| 1% to 2% | Generally healthy | Remove hard bounces right away and watch the trend |
| 2% to 5% | List quality is slipping | Re-verify the list and pause old or unverified segments |
| Above 5% | Likely list or setup problem | Stop sending, clean the list, then check authentication |
What email bounce rate means
Email bounce rate is the share of the emails you sent that came back as undeliverable. When a message cannot be delivered, the receiving mail server returns a bounce notice, and your sending tool records it. Bounce rate turns those notices into one number you can track across campaigns.
It matters because mailbox providers watch how often a sender hits addresses that do not exist. A high bounce rate suggests a sender is using an old, guessed or bought list, and that can hurt how future emails from the same domain are treated. Bounce rate is one of the earliest warning signs of a deliverability problem, often visible before open or reply rates drop.
How to calculate email bounce rate
The formula is simple:
bounce rate (%) = bounced emails / emails sent x 100
Use emails sent (or attempted) as the denominator, not emails delivered, because delivered already excludes the bounces. Many teams also track the hard bounce rate on its own, since hard bounces are the ones that signal a bad address.
Example. Maya Chen at Northwind Analytics sends a 2,400-email outbound campaign. 30 messages hard bounce and 18 soft bounce.
- Total bounce rate: 48 / 2,400 x 100 = 2.0%
- Hard bounce rate: 30 / 2,400 x 100 = 1.25%
- Soft bounce rate: 18 / 2,400 x 100 = 0.75%
The total sits at the edge of the healthy range, and most of it comes from hard bounces. That points to address quality rather than a temporary server issue, so the fix is cleaning the list, not resending.
What counts as a good bounce rate
There is no single official threshold, and different sending platforms use different cut-offs. The ranges in the table above are a widely used rule of thumb:
- Under 2% is generally considered good.
- 2% to 5% is a sign the list needs attention.
- Above 5% usually means something is wrong with the list or the sending setup.
Context changes what is realistic. Opt-in newsletters to people who recently confirmed their address often run well under 1%. Cold email runs higher because addresses come from outside sources and people change jobs, so many cold email senders set a target of under 1% to 2% and pause a campaign when it climbs past that. A single campaign with a spike matters less than a rising trend across several sends.
Hard bounces and soft bounces
Bounces fall into two groups, and they call for different responses.
A hard bounce is permanent: the mailbox does not exist, the domain does not exist, or the server refuses the message outright. Remove hard-bounced addresses from every list immediately and do not retry them.
A soft bounce is temporary: a full mailbox, a server that is briefly unavailable, or a message that is too large. Sending tools usually retry soft bounces, and many convert an address that soft bounces repeatedly into a hard bounce. Soft bounces count toward your total bounce rate, but a high soft bounce rate on its own is less of a list-quality signal than a high hard bounce rate.
Why bounce rates climb
Most high bounce rates trace back to a handful of causes, covered in more depth in why do emails bounce:
- Old lists. B2B contacts change jobs, and their old work addresses get shut down.
- Guessed addresses. Building emails from a first.last pattern without checking them.
- Unverified or bought lists. Data with no record of when or how each address was checked.
- Typos and form junk. Misspelled domains and fake sign-ups.
- Catch-all domains. A catch-all domain accepts every address at the server check, so no one can confirm a specific mailbox before you send.
- Sender-side blocks. Sudden volume spikes or missing authentication can cause receiving servers to reject messages, which also shows up as bounces.
How to lower your bounce rate
- Verify before you send. Run every new address through an email verifier, not just the list as a whole once a year.
- Remove hard bounces at once. Make suppression automatic in your sequencer.
- Re-verify aging lists. Anything that has not been checked in a few months is worth checking again before a campaign.
- Treat uncertain results as uncertain. Send to catch-all and unknown addresses at lower volume, in a separate segment, so they cannot drag down the main campaign.
- Ramp volume gradually and set up SPF, DKIM and DMARC, so receiving servers have fewer reasons to block you. See how to improve email deliverability for the full checklist.
If your contacts come from a data provider, check how it labels addresses it could not confirm. Leadsets, for example, runs every email through a verification waterfall (syntax, DNS and MX, a mailbox-level check, then a second opinion on uncertain or catch-all results) and labels each one verified, catch-all, unknown or invalid with a confidence score and the date it was checked. Uncertain results are never rounded up to valid, and invalid emails are never served as contact emails. Its email verification tool, verify_email, can also check an existing list before a send, with bulk lists running as async jobs on paid plans. In the example above, Maya could verify her next list, send to verified addresses, and put catch-alls in their own lower-volume segment. No verifier can promise zero bounces, but checking close to send time removes most of the avoidable ones.
Questions and answers
What is email bounce rate?
Email bounce rate is the percentage of emails you sent that were returned as undeliverable by the receiving mail server. It combines hard bounces, which are permanent, and soft bounces, which are temporary. It is a key early signal of list quality and deliverability.
How do you calculate email bounce rate?
Divide the number of bounced emails by the number of emails sent, then multiply by 100. For example, 48 bounces out of 2,400 sent is a 2.0% bounce rate. Many teams also calculate the hard bounce rate separately because it reflects address quality most directly.
What is a good bounce rate for cold email?
A common rule of thumb is that under 2% is good, and many cold email senders aim for under 1% to 2%. Cold lists bounce more than opt-in lists because addresses come from outside sources and people change jobs. Verifying addresses shortly before sending is the most direct way to stay in that range.
Is a 5% email bounce rate bad?
Yes, a bounce rate around or above 5% is generally treated as a problem. It usually means the list contains old, guessed or unverified addresses, or that receiving servers are blocking your messages. Pause the campaign, clean the list and check your sending setup before continuing.
Do soft bounces count toward bounce rate?
Soft bounces are usually included in the total bounce rate, but they are temporary failures such as a full mailbox or an unavailable server. Most sending tools retry them and treat repeated soft bounces as hard bounces. Tracking hard and soft bounce rates separately makes the cause easier to see.
How can I reduce my email bounce rate?
Verify addresses before sending, remove hard bounces immediately and re-verify lists that are more than a few months old. Send to catch-all and unknown addresses in a separate, lower-volume segment. Ramp sending volume gradually and set up SPF, DKIM and DMARC so servers are less likely to reject your mail.
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