Cold Email Volume Calculator
Work out how many mailboxes and domains you need to hit your daily sending target safely.
How many mailboxes and domains do you need?
The safe way to scale cold email is more mailboxes at low per-inbox volume, not a few inboxes blasting hard. A common guideline is 20 to 40 sends per mailbox per day, with a handful of mailboxes per domain so no single domain carries too much volume.
Enter your daily target and this calculator works out the mailboxes and domains you need, then prices it from Cladiant's live rates. Adjust the per-mailbox limit and mailboxes-per-domain to match your risk tolerance.
The math behind it
It's two divisions. Mailboxes needed is your daily send target divided by the safe per-mailbox limit. Domains needed is that mailbox count divided by how many mailboxes you put on each domain.
So 500 sends a day at 30 per mailbox is about 17 mailboxes; at 3 mailboxes per domain that's 6 domains. Round up at each step - it's always safer to have slightly more capacity and send under the limit than to push any single inbox harder.
Rough capacity at a glance
Assuming 30 sends per mailbox per day and 3 mailboxes per domain. Use the calculator for your exact numbers.
| Daily target | Mailboxes | Domains |
|---|---|---|
| 100 / day | ~4 | ~2 |
| 500 / day | ~17 | ~6 |
| 1,000 / day | ~34 | ~12 |
| 2,500 / day | ~84 | ~28 |
Common mistakes
The biggest one is under-provisioning and then pushing each mailbox past its limit to hit the target - which is exactly what tanks deliverability. Buy the capacity the math says you need and keep each inbox comfortably under its ceiling.
The second is forgetting warmup: new mailboxes can't send at full volume on day one, so your real capacity ramps up over the first few weeks. Plan the mailbox count for steady-state and warm them in before the campaign relies on them.
Frequently asked questions
How many emails can I send per mailbox per day?
A safe range is 20 to 40 per mailbox per day for cold outreach, ramped up gradually during warmup. Pushing higher raises spam-folder and block risk.
How many mailboxes per domain?
Keeping it to a few mailboxes per domain (commonly 1 to 5) limits how much any single domain's reputation is exposed if something goes wrong.
How do I calculate mailboxes needed?
Divide your daily send target by the safe per-mailbox limit (say 30), then divide that mailbox count by mailboxes-per-domain to get domains. Round up at each step for headroom.
Why use many mailboxes instead of a few?
Spreading volume across many low-volume mailboxes and multiple domains diversifies risk. If one inbox or domain has a problem, it doesn't take your whole campaign down.
Do I need to account for warmup?
Yes. New mailboxes ramp over two to four weeks before reaching full volume, so provision for your steady-state target and warm the mailboxes in before you depend on them.
Next steps
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