What is email bounce rate
Email bounce rate measures delivery failure. An open rate says someone looked. A bounce rate says the receiving server would not accept the message at all.
Every sending platform uses the same formula. Sent means attempted, including the messages that failed. If you divide only by mail that was delivered, the rate falls toward zero and the bad addresses disappear from the report.
Example. You attempt 10,000 messages and 180 come back. The email bounce rate is 1.8%. That sits under the 2% line. The same file with 640 bounces is 6.4%. That campaign should not have gone out. The calculator above runs this for your own report, and it splits hard and soft when you have both counts.
This is not the website bounce rate in analytics, which counts visits that leave after one page. Email bounce rate only counts mail a server refused.
A bounce is also not a spam-folder placement. Mail that lands in spam was accepted, so it never enters this number. Track complaints on their own. Google's email sender guidelines tell bulk senders to keep the Postmaster Tools spam rate under 0.10%, and to avoid ever reaching 0.30%.
Email bounce rate meaning: hard and soft
The email bounce rate meaning depends on the rejection. Mail servers answer with a status code. A 5xx code is permanent. A 4xx code is temporary. That split is the whole difference between a dead address and a bad afternoon.
Hard bounce
Permanent. The server will not accept a retry. Remove the address after one failure.
- Mailbox does not exist (SMTP 5.1.1). A typo, an invented address, or a closed account.
- Domain has no mail servers (5.1.2).
- The recipient's policy blocks you for good.
Soft bounce
Temporary. The mailbox may be real. Retry over the next day or two, then suppress it if the same address keeps failing.
- Mailbox full (4.2.2).
- Server busy, or greylisting.
- Message too large, or a short-lived policy block.
Hard bounces are a list problem. Soft bounces are often a sending problem: a volume spike, a shared IP with a bad neighbor, or an attachment the server will not take. If hard bounces are near zero and soft bounces are most of the rate, a verification tool will not fix the campaign. Slow the send and check authentication. If hard bounces are most of the rate, the addresses were never real.
Sending a hard bounce again is how Gmail and Yahoo learn that you do not know who is on the list. Google's guidelines say to confirm an address before you subscribe someone, and they explicitly allow unsubscribing people whose mail keeps bouncing.
Average email bounce rate
There is no official average email bounce rate. Mailbox providers do not publish one. What they publish is what to do when the number is bad. Google's sender guidelines say that if messages start bouncing or being deferred, cut volume until the SMTP error rate falls, then increase slowly.
These are the bands deliverability teams use on permission-based mail. They are operating limits, not a league table of industries.
| Bounce rate | What it means | What to do |
|---|---|---|
| Under 2% | Healthy for a permission list. | Keep verifying new signups. Suppress bounces as they happen. |
| 2% to 5% | The list is drifting. | Pause new segments. Verify before the next send. |
| Above 5% | Reputation risk. | Stop. Remove every hard bounce. Resume only after a fresh check is under 2%. |
Cold outbound runs higher than a newsletter, because job changes and guessed addresses are part of the file. A 2% ceiling is still the right one. "Our niche averages 4%" is not a reason to keep mailing dead inboxes. Each hard bounce is a mailbox that does not exist.
Permission lists that confirm the address at signup usually sit well under 2%, and hard bounces are a small slice of that. Purchased lists, scraped lists, and old event scans are where 5% and up shows up.
Read hard and soft separately. A 1.5% total can be a one-off soft-bounce afternoon, or it can be 1.4% hard and a dirty file. The total alone hides which fix you need. Your campaign report has the split. The calculator uses it when you paste the hard-bounce count.
How to fix a high email bounce rate
Work in this order. Warming a new domain while the file is full of dead addresses burns the new domain too.
1. Stop if you are over 5%
Pause that campaign and any automation on the same segment. Google's guidance when bounces start is to reduce volume until the error rate drops. Pushing through a dirty segment is how a domain gets throttled.
2. Suppress every hard bounce
One strike. Export the bounce file and remove those addresses from the ESP, the CRM, and every sequence. Deleting them from a single campaign leaves them in the next one.
3. Verify what is left
A syntax check will call any string shaped like an email "valid." [email protected] can be perfectly formatted and still not exist. A real check asks the mail server whether the mailbox is there, and it does not deliver a message.
Try that on one Gmail address with the free Gmail checker. For a CSV, verify the list. New accounts start with 100 verifications. The same method is what we score other tools against. The list and the rules are on How we test.
4. Confirm new addresses at the door
Double opt-in, or a live check on the signup form. Google's sender guidelines say to confirm each recipient before subscribing them, and not to buy addresses. A purchased list is a bounce-rate problem you paid for.
5. Retire repeat soft bounces
Three soft bounces across separate sends is enough. A mailbox that is "temporarily" full forever is not a customer. Suppress it the same way you suppress a hard bounce.
6. Fix the send when soft bounces dominate
Authenticate with SPF and DKIM. Add DMARC if you send in volume, with the From domain aligned to one of them. Keep a steady cadence. Do not double volume overnight. A sudden spike is a common reason a previously fine list starts soft-bouncing. Shared IPs inherit the reputation of everyone else on them.
7. Resume on a small slice
Send first to people who have opened or clicked recently. If that slice is under 2%, widen. If it is not, the verification pass missed a provider. Yahoo, AOL, and Outlook are where a cheap check returns "unknown" and the campaign still bounces.
What bounce rate does not tell you
It does not tell you inbox placement. Accepted mail can still sit in spam. It does not tell you whether a catch-all domain is a real person. Some company servers accept every address, then drop the message or bounce it later, so the first report looks clean. It does not replace a complaint check. A 0.4% bounce rate with a 0.4% spam-complaint rate is still over Google's 0.30% line.
Use the calculator for the refusal rate. Use Postmaster Tools, or your provider's equivalent, for complaints and reputation. The two numbers answer different questions.