Free tool · capacity planner
How many mailboxes and domains do you need?
Enter your daily cold-email target. We size it at the safe 10-to-20 sends per mailbox and the 2-to-3 mailboxes-per-domain ceiling, so you buy the right amount and protect placement from day one.
Your target
Cold emails per day500
505,000
Sends / day · per mailbox15
10 (safest)20 (max)
The safe cold-send band is 10 to 20 emails per mailbox per day. Below 20 protects placement; sustained sending above it correlates with decline, especially in the first 30 days after warm-up.
What you need
Mailboxes
34
Domains
12
Mailbox cost
$85/mo
34 mailboxes at $2.50 each. Domains are a one-time charge, owned by you.
To send 500 cold emails a day at a safe 15 per mailbox, you need 34 mailboxes spread across 12 domains to stay under the 2-to-3 per-domain ceiling.
Provision this in 2 minutes →Worked examples
Common targets, sized at 15 sends per mailbox.
| Cold emails / day | Mailboxes | Domains | Mailbox cost / mo |
|---|---|---|---|
| 100 | 7 | 3 | $18 |
| 250 | 17 | 6 | $43 |
| 500 | 34 | 12 | $85 |
| 1,000 | 67 | 23 | $168 |
| 2,000 | 134 | 45 | $335 |
Mailboxes = ceil(daily target / sends per mailbox). Domains = ceil(mailboxes / 3). Cost = mailboxes x $2.50.
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