Catch-all send limit calculator: how many catch-all emails can you send to?
In short: Enter how many valid, catch-all and unknown addresses you have, the bounce rate you expect from each and the most you will let the send bounce. The calculator shows how many of the risky ones fit under that ceiling. Limit: The rates are your estimates; a wrong estimate gives a wrong limit.
Enter the counts of valid, catch-all and unknown addresses from your verification report, the bounce rate you expect from each group and the highest bounce rate you will accept. The calculator works out how many risky addresses can join the send before the expected rate crosses your ceiling, and the rate you would see if you sent everything.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. Check your list free nowSee pricing
The numbers below are examples. Replace them with the counts from your verification report and the rates you expect.
From a past send to catch-all addresses, if you have one.
The most you will let this send bounce.
- Addresses you can send to
- 1,187
- Risky addresses that fit
- 187
- Expected bounce rate
- 2%
- Expected bounces
- 23.7
- Rate if you sent everything
- 3.2%
- Catch-all: 187 of 400 fit at 10% expected bounces.
Formula: the largest number x of a risky group where (valid bounces + x times its rate) divided by (valid + x) stays at or under your ceiling. The rates are your inputs, not measured figures.
Sample result
With 1,000 valid addresses and a 2% ceiling, 187 of 400 catch-all addresses fit at an expected 10% bounce rate.
- Catch-all addresses that fit
- 187 of 400
- Expected rate
- 2%
- Sending all
- 3.2%
What this means for you
Past that point the expected bounce rate crosses your ceiling; all 1,400 would be expected to bounce at 3.2%.
- Valid, catch-all and unknown groups
- Rates are yours
- Your own ceiling
- Formula shown
- Catch-all
- Bounce rate
- Calculator
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
Get the counts from a real check.
- Export the list you plan to send, or use the check button where one is offered.
- Upload or paste it at /verify. Every address gets a live mailbox check, and the first 100 email checks are free with a Google sign-in, no card.
How do I decide how many catch-all addresses to send to?
- Enter the number of valid, catch-all and unknown addresses from your verification results.
- Enter the bounce rate you expect from each group; use the rate from a past send to the same kind of addresses if you have one.
- Set the highest bounce rate you will accept for this send.
- Read how many risky addresses fit, then verify the list and send those first.
Example
- You enter
- 1,000 valid addresses expected to bounce at 0.5%, 400 catch-all addresses expected to bounce at 10%, and a ceiling of 2%.
- You get
- 187 of the 400 catch-all addresses fit. The send is 1,187 addresses with about 23.7 expected bounces, 2%. Sending all 1,400 would be expected to bounce at 3.2%.
- Limits
- Runs in your browser. The rates are the ones you enter.
How is the limit worked out?
Expected bounces are each group's count times its rate. The send's rate is total expected bounces divided by total addresses sent. The valid group goes in first. Each risky group, lowest expected rate first, then adds addresses until the rate would pass your ceiling, and groups whose rate is already under the ceiling fit entirely. If the valid group alone is over the ceiling, nothing risky fits.
Where do the rates come from?
From you; the calculator doesn't assume them. A catch-all domain accepts mail for any address, so a check can't confirm that the mailbox exists (see catch-all domains). Servers may accept a message and report a failure after the fact (RFC 5321), and the codes in a later bounce are explained in RFC 3463. The best rate to use is the one your own past sends produced; what to do with catch-all emails covers the options.
What should the ceiling be?
Whatever your sending platform allows before it acts on your account, with some room. The bounce rate calculator lists the lines platforms publish. The ceiling in the box is a starting value, not a rule.
Who uses this tool, and for what?
- Cold emailers
- Decide how many catch-all leads to add to a campaign without crossing your own bounce ceiling.
- Agencies
- Show a client the trade-off between list size and bounce rate in numbers.
- Sales ops
- Set a rule for catch-all leads that the team can follow.
What can’t this tool tell you?
- The rates are your estimates; a wrong estimate gives a wrong limit.
- It treats each group as having one steady rate, which is simpler than real lists.
- It doesn't pick which catch-all addresses to include; any order of rows gives the same expected rate.
- Platforms judge bounce rates over their own windows and counts; check yours.
Common questions
- What bounce rate does a catch-all address have?
- It depends on your list and sender, so the calculator asks you for it. A past send to catch-all addresses gives the best number.
- Does it count unknown results too?
- Yes. Add them as a second risky group with their own expected rate, or leave them empty.
- Can I send all of them if I split the sends?
- Splitting a send changes when bounces happen, not how many there are. The calculator is for one send or one period measured together.
- Does this verify anything?
- No. It is arithmetic on the numbers you enter. Verification gives you the counts.
- Is anything uploaded?
- No. The numbers stay in your browser.
Sources
A tidy list can still be full of dead addresses.
Extracting, deduplicating and syntax checks all work on the text of an address. None of them can tell whether the mailbox exists. Only the server that hosts it can answer that, through an SMTP check, and that is what the paid product 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
- Small list? Starter at $9/mo covers 2,500 emails a month, cancel anytime
Plans from $9 a month, 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.