> Enrich.chat gives AI agents verified work emails and mobiles. To use it from an agent, read https://enrich.chat/agents.md . This is the Markdown version of https://enrich.chat/blog/email-bounce-rate/

# Email bounce rate: what is a good rate, and how to lower yours

A good email bounce rate is under 2%. Here is how to calculate it, how hard and soft bounces differ, where sending platforms step in, and seven ways to bring your own rate down.

By Enrich.chat Editorial. Updated October 15, 2026.

**Short answer:** A good email bounce rate is under 2% of emails sent, and [Apollo](https://www.apollo.io/insights/whats-a-reasonable-benchmark-for-email-bounce-rates-when-using-a-paid-data-provider) adds that hard bounces should stay under 1%. [Mailgun](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/) gives 2% as its general recommendation, while [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) puts accounts under review at 5% and may pause them at 10%. Google's and Yahoo's sender rules set no bounce limit, so verify addresses first and remove hard bounces at once.

## Key takeaways

- Bounce rate is bounced emails divided by emails sent. Under 2% is the common target, per Mailgun, Mailtrap and ZeroBounce.
- A hard bounce is permanent, such as an address that does not exist. A soft bounce is temporary, such as a full mailbox. Mailchimp turns repeated soft bounces into hard ones after 7 to 15 tries.
- Sending platforms act far above the target: Amazon SES reviews accounts at 5% and may pause at 10%, Postmark pauses at 10%, and Instantly pauses campaigns above 5%.
- Google and Yahoo publish a spam complaint limit but no bounce limit. Google says to cut volume if messages start bouncing.
- Most bounces trace back to the list. In Hunter's test, accept-all addresses bounced at 27% against 1% for valid ones, so check catch-all domains before you send.

## What is email bounce rate, and how do you calculate it?

Email bounce rate is the share of the emails you send that the receiving server does not accept. To calculate it, divide the bounced emails by the emails sent and multiply by 100. [Mailtrap defines it](https://mailtrap.io/blog/email-bounce-rate/) as the percentage of emails that could not be delivered out of all emails sent, and [Klaviyo uses the same formula](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate).

Take a send of 10,000 emails with 40 hard bounces and 120 soft bounces. That is 160 bounces, so the bounce rate is 160 divided by 10,000, or 1.6%. The hard bounce rate on its own is 0.4%.

**Figure 1: How email bounce rate is calculated.** An illustrative send of 10,000 emails. 40 hard bounces plus 120 soft bounces make 160 bounces. 160 bounces divided by 10,000 sent gives a bounce rate of 1.6%. A tool that counts only hard bounces, as Amazon SES does, reports 0.4% for the same send.

*Illustrative example of one send. The same bounces give 1.6% or 0.4%, depending on whether a tool counts soft bounces. Counting methods from [Klaviyo](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate), [Mailtrap](https://mailtrap.io/blog/email-bounce-rate/) and [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html).*

Check which bounces your tool counts, because the rules differ.

- **Amazon SES** bases its bounce rate on hard bounces and [leaves out soft bounces](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html). It also [ignores automatic replies](https://docs.aws.amazon.com/ses/latest/dg/notification-contents.html), such as out-of-office messages.
- **Postmark** counts the bounce events marked in red in its stats, [except](https://postmarkapp.com/support/article/does-postmark-have-a-daily-send-limit) bounces to blackhole addresses, bounces on a sandbox server and SMTP API errors.
- **Klaviyo and Mailtrap** count every bounce against the total sent.

Some bounces also arrive late. In an asynchronous bounce, the receiving provider accepts the message first and reports the failure afterward, as [Twilio SendGrid's documentation](https://www.twilio.com/docs/sendgrid/ui/sending-email/bounces) explains. Read your rate again a day or two after a large send.

## What is a good email bounce rate?

A good email bounce rate is under 2% of emails sent. [Mailgun](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/) gives 2% as its general recommendation and says a zero bounce rate is the goal but not realistic. [Mailtrap](https://mailtrap.io/blog/email-bounce-rate/) calls under 2% normal, 2% to 5% a warning and above 5% critical. [ZeroBounce](https://www.zerobounce.net/blog/email-resources/email-verification/email-bounce-rate-benchmark) treats under 1% as ideal.

Hard bounces need a tighter limit, because they point to addresses that do not exist. [Apollo](https://www.apollo.io/insights/whats-a-reasonable-benchmark-for-email-bounce-rates-when-using-a-paid-data-provider), a contact data vendor, targets under 2% in total and hard bounces ideally below 1%.

### What is a good bounce rate for cold email?

Cold email platforms use the same 2% line. [Smartlead](https://www.smartlead.ai/blog/cold-email-bounce-rate) says a good rate is below 2% on a rolling 14-day window and calls 2% to 4% a warning zone. Its State of Cold Email 2026 report, which covers more than 850 million sends, puts the median sender at 1.54% and the 75th percentile at 3.21%. [lemlist](https://help.lemlist.com/en/articles/4511285-understanding-and-reducing-bounces-a-comprehensive-guide) advises staying under 3%. These are vendor figures, not rules set by inbox providers. Our guide to [cold email data](https://enrich.chat/blog/cold-email/) covers lists and verification in more depth.

### Why not use industry averages?

Industry averages vary too much to trust. [ZeroBounce's benchmark post](https://www.zerobounce.net/blog/email-resources/email-verification/email-bounce-rate-benchmark) lists averages such as 0.57% for e-commerce and credits them to Mailchimp. But [Mailchimp's benchmark page](https://mailchimp.com/resources/email-marketing-benchmarks/), last updated in December 2023, shows open, click and unsubscribe rates and no bounce rates. [Mailtrap](https://mailtrap.io/blog/email-bounce-rate/) adds that the source of an analysis changes the averages a lot, and that the acceptable rate stays below 2% either way. Aim for under 2%, and compare yourself with your own past sends.

## At what bounce rate do email providers step in?

Sending platforms step in at 5% to 10%, well above the 2% target. Google and Yahoo name no bounce limit in their sender rules. The table shows what each source says in its own documentation.

| Source | Bounce limit | What happens |
| --- | --- | --- |
| [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) | 5% of hard bounces | The account goes under review automatically. At 10% SES might pause sending. |
| [Postmark](https://postmarkapp.com/support/article/does-postmark-have-a-daily-send-limit) | 10% of all emails sent | Accounts at or above it are contacted and paused. |
| [Instantly](https://help.instantly.ai/en/articles/9823139-high-bounce-auto-pause-feature) | 5% by default, after 200 emails | The campaign pauses on its own. You can change the threshold. |
| [lemlist](https://help.lemlist.com/en/articles/4511285-understanding-and-reducing-bounces-a-comprehensive-guide) | Under 3% advised | Its guide says to pause campaigns above 5%. |
| [Mailchimp](https://mailchimp.com/help/about-bounce-suspension/) | Number not published | Sending is suspended when a single send has too many hard bounces. |
| [Google (Gmail)](https://support.google.com/a/answer/81126) | No bounce limit | Keep the spam rate below 0.10% and never reach 0.30%. Cut volume if messages start bouncing. |
| [Yahoo](https://senders.yahooinc.com/best-practices/) | No bounce limit | Keep the spam rate below 0.3% and remove invalid recipients promptly. |

**Figure 2: Bounce rate limits set by email sources.** A bar chart of bounce rate limits. Mailgun recommends under 2% and lemlist advises under 3%. Instantly pauses campaigns above 5%, and Amazon SES puts an account under review at 5%. Amazon SES may pause sending at 10% and Postmark pauses accounts at 10%. A dashed line marks the 2% target.

*Recommended limits (blue) and the points where providers act (dark). Amazon SES counts hard bounces only, Postmark counts bounces as a share of all emails sent, and Instantly checks only after a campaign has sent 200 emails. Sources: [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html), [Postmark](https://postmarkapp.com/support/article/does-postmark-have-a-daily-send-limit), [Instantly](https://help.instantly.ai/en/articles/9823139-high-bounce-auto-pause-feature), [Mailgun](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/) and [lemlist](https://help.lemlist.com/en/articles/4511285-understanding-and-reducing-bounces-a-comprehensive-guide).*

A missing number is not permission to ignore bounces. [Amazon SES lists attempted deliveries to invalid addresses](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) among the signals mailbox providers use when they flag a sender. [Postmark](https://postmarkapp.com/blog/pay-close-attention-to-bounces) says inbox providers read a high bounce rate as low-quality sending behavior. [Google's sender guidelines](https://support.google.com/a/answer/81126) tell senders to unsubscribe recipients who have multiple bounced messages, and to reduce volume if messages start bouncing or being deferred.

Treat 2% as your line and 5% as your alarm. Most sending platforms publish a number and enforce it. Inbox providers do not.

## What is the difference between a hard bounce and a soft bounce?

A hard bounce is a permanent delivery failure, usually because the address does not exist. A soft bounce is a temporary failure, such as a full mailbox or a server that is down. [Mailchimp](https://mailchimp.com/help/soft-vs-hard-bounces/) sorts every bounce into these two groups, using the reason the receiving server gives.

|  | Hard bounce | Soft bounce |
| --- | --- | --- |
| SMTP reply | 5yz, permanent | 4yz, temporary |
| Typical causes | Address does not exist, a typo, a closed account, a permanent block | Full mailbox, server down, message too large, mail arriving too fast |
| Example code | 550 5.1.1, address does not exist | 450 4.2.1, receiving mail too quickly |
| What platforms do | Suppress the address at once | Retry, then suppress after repeats |
| What you do | Remove it from every list | Watch it, and remove repeat offenders |

Two standards sit behind these labels. Under [RFC 5321](https://www.rfc-editor.org/rfc/rfc5321.html), a 5yz reply means the command was not accepted and the sender should not repeat the exact request. A 4yz reply means the error is temporary and the request may be tried again. [RFC 3463](https://www.rfc-editor.org/rfc/rfc3463.html) adds a status code in the form class.subject.detail, where class 5 is a permanent failure and class 4 is a transient one. Its X.1.1 code means the destination mailbox address is bad.

**Figure 3: Two bounce codes, decoded.** Two example bounce codes side by side. The hard bounce 550 5.1.1 starts with 5, a permanent reply that should not be repeated, and X.1.1 means a bad mailbox address, so Gmail says the address does not exist and you should suppress it at once. The soft bounce 450 4.2.1 starts with 4, a temporary reply, and Gmail says the recipient is receiving mail too quickly, so you retry and count repeats.

*How to read a bounce code. The first digit of the reply tells you whether to retry, per [RFC 5321](https://www.rfc-editor.org/rfc/rfc5321.html) and [RFC 3463](https://www.rfc-editor.org/rfc/rfc3463.html). The two examples and their meanings come from [Google's Gmail SMTP error list](https://knowledge.workspace.google.com/admin/support/troubleshooting/gmail-smtp-errors-and-codes).*

Google's list of Gmail SMTP errors shows how this looks in practice. A 550 5.1.1 error means the address does not exist. A 421, 450 or 451 reply is temporary, and Google says to retry later.

### Does every hard bounce mean the contact is dead?

No. A hard bounce can also be a block on your side. Google's 550 5.7.1 error means a policy or spam filter blocked the message, and its 5.7.26 error means the message failed sender authentication. [Mailchimp notes](https://mailchimp.com/help/soft-vs-hard-bounces/) that valid addresses sometimes hard bounce too. Read the error code before you delete a lead.

### When does a soft bounce become a hard bounce?

Each platform sets its own rule. [Mailchimp](https://mailchimp.com/help/soft-vs-hard-bounces/) converts a soft bounce to a hard one after 7 soft bounces for an address with no activity, and up to 15 for contacts with earlier activity. [Klaviyo](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate) suppresses an address that soft bounces more than 7 consecutive times. [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/notification-contents.html) keeps retrying a soft bounce for a set time, then stops and reports it. [Postmark](https://postmarkapp.com/blog/pay-close-attention-to-bounces) takes no automatic action on soft bounces, but warns that enough of them can hurt your domain's reputation.

## What causes a high email bounce rate?

Most high bounce rates start with the list, not the message. These are the causes the sources in this guide name most often.

- **Typos.** [Postmark says typos are the most common cause of hard bounces](https://postmarkapp.com/blog/pay-close-attention-to-bounces). One wrong letter makes an address that does not exist.
- **People who left.** [Mailgun lists closed accounts and departed employees](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/) among hard bounce causes. The [US Bureau of Labor Statistics](https://www.bls.gov/news.release/tenure.nr0.htm) reports a median job tenure of 4.1 years in January 2026, and 3.0 years for workers aged 25 to 34. Every job change can end a work email. Our guide to [how fast B2B contact data goes bad](https://enrich.chat/blog/b2b-data-decay/) covers this in more detail.
- **Guessed addresses.** A pattern such as first.last@company.com is a guess. If the mailbox is not there, the server answers 550 5.1.1. Learn the common [business email formats](https://enrich.chat/blog/email-address-formats/), but check a guess before you send to it.
- **Catch-all domains.** A catch-all server accepts every address, then may reject mail later. In [Hunter's test](https://hunter.io/email-verification-guide/accept-all-catch-all/), 100 accept-all addresses bounced at 27% and 100 valid addresses bounced at 1%. That is one small test by a verifier vendor, but the gap is wide. Test a domain with the free [catch-all checker](https://enrich.chat/tools/catch-all-checker/).
- **Old or bought lists.** [Spamhaus explains](https://www.spamhaus.org/resource-hub/deliverability/spamtraps-fix-the-problem-not-the-symptom/) that abandoned addresses hard bounce for a period, often 12 months or more, and are then silently turned back on as spam traps. [Amazon SES says](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) purchased lists can contain spamtrap addresses.
- **Blocks and failed authentication.** Some bounces are about you. [Google requires](https://support.google.com/a/answer/81126) SPF or DKIM from every sender to Gmail, and SPF, DKIM and DMARC from bulk senders of 5,000 or more messages a day. [Mailchimp](https://mailchimp.com/help/soft-vs-hard-bounces/) tells senders to authenticate their domain and set up DMARC to prevent bounces.
- **Sending too fast.** Gmail answers 450 4.2.1 when a recipient is receiving mail too quickly, and [Google says to raise volume slowly](https://support.google.com/a/answer/81126).
- **Full or inactive mailboxes.** These cause soft bounces, per [Mailchimp's list of common reasons](https://mailchimp.com/help/soft-vs-hard-bounces/).

## How do you lower your email bounce rate?

You lower your bounce rate by keeping bad addresses off the list and acting on every bounce. These seven steps do both.

1. **Confirm addresses at sign-up.** [Yahoo's sender guide](https://senders.yahooinc.com/best-practices/) and [Klaviyo](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate) both recommend double opt-in, where each person confirms their address. It keeps typos and fake addresses off the list. For prospect lists you did not collect yourself, go to step 2.
2. **Verify before the first send.** [Mailgun says](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/) you can avoid hard bounces by verifying a list before you send to it. Re-check anything old. [Smartlead](https://www.smartlead.ai/blog/cold-email-bounce-rate) says to re-verify every address not checked in the last 90 days, and [Apollo](https://www.apollo.io/insights/whats-a-reasonable-benchmark-for-email-bounce-rates-when-using-a-paid-data-provider) gives the same 90-day rule for older segments.
3. **Handle risky addresses on their own.** [Smartlead](https://www.smartlead.ai/blog/cold-email-bounce-rate) says to leave out catch-all addresses and role addresses such as info@ and sales@. [Hunter](https://hunter.io/email-verification-guide/accept-all-catch-all/) suggests keeping accept-all addresses to 2% to 5% of a list. [Spamhaus](https://www.spamhaus.org/resource-hub/deliverability/spamtraps-fix-the-problem-not-the-symptom/) says role addresses like postmaster@ should almost never be on a marketing list.
4. **Suppress every hard bounce at once, in every tool.** [Amazon SES says to remove a hard-bounced address immediately](https://docs.aws.amazon.com/ses/latest/dg/notification-contents.html), and [Mailgun](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/) suggests adding it to a suppression list instead of deleting the contact. Copy the same list to your CRM and any other sender, so no tool emails it again.
5. **Set a limit for soft bounces.** Pick a rule and apply it every time. [Klaviyo suggests](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate) a segment of anyone with at least four bounced emails in the last 90 days.
6. **Authenticate your domain and add volume slowly.** Set up SPF, DKIM and DMARC. [Google says](https://support.google.com/a/answer/81126) to cut volume back if messages start bouncing or being deferred, then raise it slowly.
7. **Track the rate by segment and mailbox.** A blended rate hides the problem. [Smartlead](https://www.smartlead.ai/blog/cold-email-bounce-rate) watches each mailbox on a rolling 14-day window, because a fleet average can hide the mailbox in trouble. [Apollo](https://www.apollo.io/insights/whats-a-reasonable-benchmark-for-email-bounce-rates-when-using-a-paid-data-provider) suggests a pilot send of 200 to 500 contacts, with a look at bounces within 48 hours, before you scale a new segment.

## What should you do if your bounce rate is already too high?

Pause sending to the affected segment first, then find where the bad addresses came from. [Apollo's playbook](https://www.apollo.io/insights/whats-a-reasonable-benchmark-for-email-bounce-rates-when-using-a-paid-data-provider) says to pause the affected segments and re-verify them when the rate is between 2% and 5%, and to stop all sends above 5%. [lemlist](https://help.lemlist.com/en/articles/4511285-understanding-and-reducing-bounces-a-comprehensive-guide) also says to pause campaigns above 5%, and [Instantly](https://help.instantly.ai/en/articles/9823139-high-bounce-auto-pause-feature) pauses them for you and asks you to verify your leads.

1. **Group the bounces.** Sort them by error code, recipient domain and list source. A 550 5.1.1 error points to bad addresses. A 5.7.1 or 5.7.26 error points to filtering or authentication. A 4yz error points to rate or server limits. Instantly's campaign analytics has a Bounces tab that lists the types and reasons.
2. **Remove hard bounces and repeat soft bounces.** Add them to your suppression list in every tool.
3. **Re-verify the rest.** Hold back catch-all and role addresses until you have a second sign they are real.
4. **Fix authentication** if the codes point to it.
5. **Tell your platform what you changed.** [Amazon SES says](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) that if you describe your fixes in the support case and it agrees they will lower your rate, it recalculates using only the bounces received after the changes.
6. **Restart in small batches.** [Google advises](https://support.google.com/a/answer/81126) reducing volume until the SMTP error rate falls, then increasing it slowly.

## How can Enrich.chat help you keep bounces low?

Enrich.chat gives your AI agent a status for every work email it returns, so the agent can choose which addresses to send to first. It does not send email and it does not manage your suppression list. It is a contact data API that your agent learns from one prompt.

Each work email comes back with a status from our records: `verified`, `catch_all` or `unknown`. Catch-all means the domain accepts every address, so the address cannot be confirmed. When nothing matches, the response says `found` is false and the lookup uses 0 credits. A work email that is found uses 10 credits.

Here is a simple rule your agent can follow:

- **verified:** send first, in small batches.
- **catch_all:** hold until you have a second sign the person is real, or keep these to a small share of each batch, as [Hunter suggests](https://hunter.io/email-verification-guide/accept-all-catch-all/).
- **unknown:** leave out until you can check the address another way.
- **not found:** there is nothing to send and nothing used.

A status is not a guarantee. Treat every address as a strong lead, keep your own suppression list, and watch the bounce rate of your first batch. Here is a prompt that sorts a list this way.

```text
Use www.enrich.chat to find the work email for each person in this list of names and company websites. Show the status of every email, and put the catch_all and unknown results in a separate list that I should hold back from my first send.
```

You can try it with no signup. The API gives 10 free lookups a day, then monthly credit plans from $29 for 100,000 credits, billed monthly. See the [Enrich.chat pricing page](https://enrich.chat/pricing/), learn how [AI agents use the API](https://enrich.chat/agents/), or read about the [email finder API](https://enrich.chat/api/email-finder/). The free [email finder](https://enrich.chat/tools/email-finder/) works in your browser. For the full outbound workflow, read [cold email in 2026: the data side](https://enrich.chat/blog/cold-email/), and see [CRM data enrichment](https://enrich.chat/blog/crm-data-enrichment/) for keeping saved records current.

## Frequently asked questions

### How do you calculate email bounce rate?

Divide the number of bounced emails by the number of emails sent, then multiply by 100. [Klaviyo](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate) uses that formula, so 100 bounces from 5,000 emails is 2%. Check which bounces your tool counts. [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) counts hard bounces only, and [Postmark](https://postmarkapp.com/support/article/does-postmark-have-a-daily-send-limit) leaves out sandbox and blackhole bounces, so two tools can report different rates for the same send.

### Is a 20% email bounce rate bad?

Yes. A 20% bounce rate is far past every limit in this guide. [Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html) may pause sending at 10%, and [Postmark](https://postmarkapp.com/support/article/does-postmark-have-a-daily-send-limit) pauses accounts at 10%. Stop sending to that list, group the bounces by error code, and remove every hard bounce. Then re-verify what is left before you send again, and restart in small batches.

### What is a good bounce rate for cold email?

Aim for under 2%. [Smartlead](https://www.smartlead.ai/blog/cold-email-bounce-rate) calls under 2% on a rolling 14-day window good and 2% to 4% a warning zone, while [lemlist](https://help.lemlist.com/en/articles/4511285-understanding-and-reducing-bounces-a-comprehensive-guide) advises under 3%. [Instantly](https://help.instantly.ai/en/articles/9823139-high-bounce-auto-pause-feature) pauses a campaign above 5% by default once it has sent 200 emails. Verify every address first, and read our guide to the [data side of cold email](https://enrich.chat/blog/cold-email/).

### What causes a soft bounce?

A soft bounce comes from a temporary problem. [Mailchimp](https://mailchimp.com/help/soft-vs-hard-bounces/) lists a full or inactive mailbox, an offline server, too many emails sent in a period, and a message that is too large. [Google](https://knowledge.workspace.google.com/admin/support/troubleshooting/gmail-smtp-errors-and-codes) returns 450 4.2.1 when a recipient is receiving mail too quickly. Soft bounces often clear by themselves, but repeats on one address are treated as hard bounces.

### Do soft bounces hurt sender reputation?

They can. [Postmark](https://postmarkapp.com/blog/pay-close-attention-to-bounces) warns that enough soft bounces over time can affect your domain's reputation. Platforms also turn repeat soft bounces into hard ones. [Mailchimp](https://mailchimp.com/help/soft-vs-hard-bounces/) does it after 7 soft bounces for an address with no activity, and up to 15 for contacts who engaged before. [Klaviyo](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate) suppresses an address after more than 7 in a row.

### How can you tell if an email bounced?

Look for a bounce message from the receiving server, or check your sending tool's report. [Instantly](https://help.instantly.ai/en/articles/9823139-high-bounce-auto-pause-feature) says a bounce report arrives with error codes and explanations from the recipient's server. A 5yz code is permanent and a 4yz code is temporary, as [RFC 5321](https://www.rfc-editor.org/rfc/rfc5321.html) defines them. In [Mailchimp](https://mailchimp.com/help/soft-vs-hard-bounces/), bounce receipts stay in your email reports for 30 days.

## Sources

1. [Reputation metrics messages](https://docs.aws.amazon.com/ses/latest/dg/reputationdashboardmessages.html)
2. [Amazon SNS notification contents for Amazon SES](https://docs.aws.amazon.com/ses/latest/dg/notification-contents.html)
3. [Does Postmark have a daily send limit?](https://postmarkapp.com/support/article/does-postmark-have-a-daily-send-limit)
4. [Pay close attention to bounces](https://postmarkapp.com/blog/pay-close-attention-to-bounces)
5. [High Bounce Auto-Pause Feature](https://help.instantly.ai/en/articles/9823139-high-bounce-auto-pause-feature)
6. [Reduce email bounces](https://help.lemlist.com/en/articles/4511285-understanding-and-reducing-bounces-a-comprehensive-guide)
7. [Cold email bounce rate: what's good and how to fix it](https://www.smartlead.ai/blog/cold-email-bounce-rate)
8. [What's a Good Email Bounce Rate for Paid Data?](https://www.apollo.io/insights/whats-a-reasonable-benchmark-for-email-bounce-rates-when-using-a-paid-data-provider)
9. [Email bounces: What to do about them](https://www.mailgun.com/blog/deliverability/email-bounces-what-to-do-about-them/)
10. [Email Bounce Rate: Definition, Benchmark, Best Practices](https://mailtrap.io/blog/email-bounce-rate/)
11. [The Email Bounce Rate Benchmark](https://www.zerobounce.net/blog/email-resources/email-verification/email-bounce-rate-benchmark)
12. [Soft vs. Hard Bounces](https://mailchimp.com/help/soft-vs-hard-bounces/)
13. [About Bounce Suspension](https://mailchimp.com/help/about-bounce-suspension/)
14. [Email Marketing Benchmarks](https://mailchimp.com/resources/email-marketing-benchmarks/)
15. [How to decrease bounce rates](https://help.klaviyo.com/hc/en-us/articles/360057036052-How-to-Decrease-Bounce-Rate)
16. [Email sender guidelines](https://support.google.com/a/answer/81126)
17. [Gmail SMTP errors and codes](https://knowledge.workspace.google.com/admin/support/troubleshooting/gmail-smtp-errors-and-codes)
18. [Sender best practices](https://senders.yahooinc.com/best-practices/)
19. [Manage bounced messages](https://www.twilio.com/docs/sendgrid/ui/sending-email/bounces)
20. [RFC 5321: Simple Mail Transfer Protocol](https://www.rfc-editor.org/rfc/rfc5321.html)
21. [RFC 3463: Enhanced Mail System Status Codes](https://www.rfc-editor.org/rfc/rfc3463.html)
22. [What Are Accept-all Email Addresses, and How to Use Them](https://hunter.io/email-verification-guide/accept-all-catch-all/)
23. [Spamtraps: fix the problem, not the symptom](https://www.spamhaus.org/resource-hub/deliverability/spamtraps-fix-the-problem-not-the-symptom/)
24. [Employee Tenure in 2026](https://www.bls.gov/news.release/tenure.nr0.htm)

## Try this prompt

Sort work emails by bounce risk

```text
Use www.enrich.chat to find the work email for each person in this list of names and company websites. Show the status of every email, and put the catch_all and unknown results in a separate list that I should hold back from my first send.
```

## Related

- [Cold email: the data side](https://enrich.chat/blog/cold-email/)
- [Catch-all email checker](https://enrich.chat/tools/catch-all-checker/)
- [How fast B2B contact data goes bad](https://enrich.chat/blog/b2b-data-decay/)