Email list bounce rate estimator: how much will this list bounce?
You can estimate part of a list's bounce rate before sending. Paste the list here and the estimator counts addresses that will bounce (bad syntax, domains with no mail server) and those likely to (typo domains, disposable inboxes, role addresses), then gives a range. It's an estimate: mailboxes that closed on working domains can't be seen without a verification, so the real rate can be higher.
Sample result
Estimated bounce rate: at least 22%, up to 56% from problems visible in the addresses.
- Estimate
- 22% to 56%
- Will bounce
- 2
- Likely to bounce
- 3
What this means for you
That's over the 2% line before any closed mailbox is counted. An estimate, not a verification.
- Bad syntax and dead domains: will bounce
- Typos, disposable and role rows: likely
- Paste a list or enter counts
- 500 rows a run, 5,000 signed in
- Bounce rate
- Estimate
- MX
By SimpleVerifier Team · Last updated
How to estimate an email list's bounce rate before sending
- Paste one address per line or upload a CSV, or switch to Enter counts if you already have the numbers from another report.
- Press Estimate the bounce rate. Syntax, duplicates, typos and role addresses are checked in your browser; only the unique domains are sent, for an MX lookup.
- Read the range: the floor is what will certainly bounce, the top adds what is likely to.
- Download the risky rows, then verify the rest before you send.
Example
- You enter
- Ten rows:
jane@acme.com,sam@gmial.com,lee@gmail.comtwice,postmaster@contoso.com,temp123@mailinator.com,ana@shop.example,pat@stripe.com,kai at yahoo.comandmia@outlook.com. - You get
- One duplicate is left out, leaving 9 rows. Will bounce: 2 (
kai at yahoo.comhas invalid syntax,shop.examplehas no mail server). Likely to bounce: 3 (a typo of gmail.com, a disposable inbox, an operations role address). Estimated range 22% to 56%, with the other 4 rows only a verification can settle. - Limits
- Up to 500 rows a run without an account and 5,000 when signed in with Google; only the unique domains are sent, for an MX lookup. The Enter counts tab has no limit.
How is the bounce rate estimated?
Every row goes into one of three groups. Will bounce: the address isn't validly formed, or its domain has no mail server at all (no MX and no A record, or a null MX that says it takes no mail, per RFC 7505). Likely to bounce: the domain looks like a typo of a big mail domain (gmial.com), the address is on a disposable inbox service, or it's an operations role address such as postmaster@ or noreply@. Can't tell: everything else.
The floor of the range is the first group divided by the list's unique rows; the top adds the second group. Duplicates are left out, because a repeat of a good address doesn't bounce; it's sent twice. These are the same checks as the list health check, counted as a rate.
Why is it only an estimate?
Because the biggest cause of hard bounces on an aging list is invisible from the outside: a mailbox that has been closed on a domain that still works, such as someone who left a company. The address and domain look fine, so it lands in Can't tell. Only asking the receiving mail server, which is what email verification does, can settle those rows. The more time since the list was collected, the more of them there are; the list decay calculator models that.
"Likely" rows aren't certain either. Some typo domains are registered and accept mail, and some role addresses do reach a person. They're counted in the top of the range because they bounce often enough to matter.
What bounce rate is too high?
Sending platforms set their own limits, and the lowest published one we know of is Brevo's 2%; the bounce rate calculator lists each platform's line. If the floor here is already over 2%, the list will cross that line from visible problems alone, before any closed mailbox is counted. The platforms' rules are collected in bounce rate limits by platform.
Estimate, list health check or verification?
| This estimator | List health check | Verification | |
|---|---|---|---|
| Question | How much will this list bounce? | Which rows have visible problems? | Does each mailbox exist? |
| Contacts the mail server | No | No | Yes, without sending |
| Closed mailboxes | Not seen | Not seen | Found |
| Output | A bounce rate range | Cleaned list and problem rows | Status for every address |
Who uses this tool, and for what?
- Email marketers
- Check an old or imported list before it goes into a campaign that a high bounce rate could pause.
- Cold emailers
- Size the visible problems in a scraped or purchased list before you load it into a sending tool.
- Agencies
- Show a client, with numbers from their own list, why it needs cleaning before the first send.
- Lead buyers
- Compare two vendors' samples by how much of each will bounce from visible problems alone.
What can’t this tool tell you?
- It's an estimate, not a verification: closed mailboxes on working domains aren't counted, so the real rate can be higher.
- Typo, disposable and role rows are likely to bounce, not certain to.
- A domain whose DNS doesn't answer in time is kept in Can't tell, never counted as dead.
- 500 rows a run without an account, 5,000 signed in.
Common questions
- Can you predict an email bounce rate before sending?
- Partly. Addresses with bad syntax or dead domains will bounce, and typos, disposable inboxes and role addresses often do, so those can be counted in advance. Closed mailboxes on working domains can't be seen without verification, so a prediction from the addresses alone is a minimum, not the full rate.
- Is this an email verification?
- No. It never contacts a mail server or checks a mailbox. It counts problems visible in the text of each address and in its domain's DNS, and labels the result as an estimate.
- How many addresses can I estimate at once?
- 500 rows a run without an account and 5,000 when you sign in with Google. The Enter counts tab has no limit, because it only does the arithmetic.
- Is my list uploaded?
- No. The list is read in your browser. Only the unique domains, the part after the @, are sent to our server for the MX lookup, and nothing is stored.
- Why are duplicates not counted as bounces?
- A duplicate of a working address is delivered twice, not bounced, so it's left out of the rate. Remove duplicates anyway; the remove duplicate emails tool does it with your columns kept.
- What's the difference from the bounce rate calculator?
- The bounce rate calculator works after a send, from the bounces you actually got. This estimator works before a send, from the list itself.
Sources
Every address left in your cleaned list still need a mailbox check.
This tool removed what can be found without contacting a mail server. Whether each remaining mailbox actually exists can only be answered by asking the server that hosts it — an SMTP check — and that is what the paid plan does.
- Upload the cleaned file as it is — CSVs up to 100,000 rows
- A real SMTP mailbox check on every row, with catch-all detection
- Valid, risky and invalid exported as separate files
One plan, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.