Your email bounce rate is the share of sent emails that came back undelivered: bounces divided by emails sent, times 100. A good bounce rate is below 2%, and well-kept lists stay under 1%. Above that, email services start to act: Amazon SES puts accounts under review at a 5% hard bounce rate, and several others name 5% as their limit. This guide shows how to measure the rate, what the published benchmarks and limits are, and how to bring it down.
How to calculate your bounce rate
bounce rate = bounced emails ÷ emails sent × 100
120 bounces out of 10,000 emails sent is a bounce rate of 1.2%. Calculate it per campaign and over time, and look at the hard bounce rate on its own: hard bounces are addresses or domains that don’t exist, and they are what email services and mailbox providers react to. Try your own numbers:
Bounce rate calculator
Hard bounce rate
1.20%
Total bounce rate (hard + soft)
1.80%
Below 2%: in the range mailbox providers and email services expect.
Two details change the result. Some tools divide by emails sent, others by emails attempted, so compare rates from the same tool only. And a bounce can arrive minutes or days after the send: a server may accept a message first and send the bounce later, so wait a day before you judge a campaign.
What is a good email bounce rate?
There is no official number, but email services publish what they see across their customers. The figures differ because each counts differently and covers a different year:
| Source | Average bounce rate | What it measures | Data from |
|---|---|---|---|
| Twilio SendGrid, 2023 benchmark report | 1.06% (median 0.21%) | Bounce rate across more than 5 trillion emails | 2022 |
| Validity, 2026 deliverability benchmark | 1.46% | “Unknown user” rate, Validity’s term for hard bounces | 2025 |
| GetResponse email marketing benchmarks | 2.33% | Bounce rate, hard and soft not split | 2023 |
| MailerLite | 0.55% | Average across MailerLite customers | 2021 |
The median in SendGrid’s report is the useful number: most senders bounce far less than the average, which a few senders with bad lists pull up. If your rate is above 1%, your list is worse than most; above 2%, clean it before the next send.
The limits email services enforce
Your email service watches your bounce rate because your bounces hurt the reputation of its sending IPs. These are the limits they publish:
| Service | Limit | What counts |
|---|---|---|
| Amazon SES | Recommended below 2%; account review at 5%; sending may be paused at 10% | Hard bounces to domains you haven’t verified |
| Twilio SendGrid | Hard bounces from fewer than 5% of attempted messages | Hard bounces |
| Mailgun | Bounces at or below 5% (acceptable use policy) | All bounced messages |
| HubSpot | 5% hard bounce rate in a month can suspend marketing email | Hard bounces |
| Postmark | Below 10%; “well under 5%” is healthy | All bounces |
| Klaviyo | Below 1% healthy, 1–2% room for improvement, above 2% needs attention | All bounces |
| Mailchimp | Look at your list above 2%, review it urgently above 5% (guidance) | Campaign bounces |
Amazon SES itself names two targets: its enforcement FAQ recommends staying below 2%, while its reputation dashboard recommends below 5%. Treat 2% as the line to stay under and 5% as the point where services act. Mailbox providers such as Gmail and Microsoft don’t publish a bounce number, but count mail to unknown addresses against your sender reputation; how reputation, authentication and list quality work together is covered in the email deliverability guide.
Hard bounces, soft bounces and blocks
Not every bounce means the same thing, and only some of them say anything about the address:
| Type | Cause | Typical codes | What to do |
|---|---|---|---|
| Hard bounce | The mailbox or domain doesn’t exist | 550 5.1.1, 550 5.1.10 | Remove the address at once |
| Soft bounce | Full mailbox, server busy or down, greylisting | 452 4.2.2, 421, 451 | Retry; remove after several failures in a row |
| Block | The receiver refused your message, not the address | 550 5.7.1, 550 5.7.26 | Fix authentication or reputation; the address may be fine |
The guide to hard vs. soft bounces explains each type in detail, and the SMTP error codes reference decodes the message in any bounce.
Why bounce rates go up
- Lists age. People change jobs, companies change domains, and free mailboxes are closed after years without use. A list you haven’t mailed in a year has decayed, even if every address was fine when it was collected.
- Typos at sign-up.
anna@gmial.compasses every format check and bounces on the first send. - Imports and purchased lists. Addresses from trade shows, old CRMs or list vendors were never confirmed by their owners.
- Disposable addresses. Throwaway inboxes stop working within hours or days.
- Catch-all domains. Some accept mail at first and bounce it later; see catch-all email.
8 ways to reduce your email bounce rate
- Validate at sign-up. Stop typos and made-up addresses at the source with a real-time check from the email validation API, and show a “did you mean” hint for misspelled domains. To check a single address by hand, use the free email checker.
- Verify old lists before you send. Run a list that hasn’t been mailed in months through the email list cleaning service (up to 100,000 addresses per job), or check a few addresses with the free bulk email verifier, and remove the undeliverable ones. The guide to email verification explains what these checks can and can’t detect.
- Use double opt-in for newsletters, so only addresses whose owners clicked the confirmation link get on the list.
- Block disposable addresses at sign-up; the disposable email checker shows whether a domain is one.
- Set up SPF, DKIM and DMARC, so receivers don’t reject your mail as unauthenticated. Build the records with the SPF record generator and the DMARC generator, and check them with the SPF, DKIM and DMARC checkers. Since 2024, Gmail and Yahoo require this from bulk senders; the sender requirements list the details.
- Remove hard bounces automatically, and stop sending to an address after several soft bounces in a row. Most email services do the first for you; check that the suppression list is on.
- Sunset inactive contacts. Addresses that haven’t opened or clicked in 6 to 12 months are where the next bounces come from. Send them a re-engagement email, then remove those who don’t respond.
- Treat catch-all addresses separately. Send to them in smaller batches and watch the bounces before you add them to your main list.
When the bounces are in your inbox
If you send from Gmail or Outlook rather than an email service, bounces arrive as messages from “Mail Delivery Subsystem” or “MAILER-DAEMON”, or with the subject “Undeliverable:”. The guide to Mail Delivery Subsystem emails shows how to read them, and how to tell real bounces from backscatter and phishing.
Sources
Checked October 29, 2026: Amazon SES enforcement FAQ and reputation metrics; Twilio SendGrid bounce and block classifications and 2023 benchmark report; Mailgun acceptable use policy; HubSpot, why is my email suspended; Postmark, daily send limits and troubleshooting delivery; Klaviyo benchmarks; Mailchimp, how to reduce email bounce rates; Validity 2026 benchmark report; GetResponse benchmarks; MailerLite on bounced emails.