How many mailboxes do you need?
Start from the meetings you want or the emails you want to send each day. The calculator sizes the fleet at a safe per-mailbox volume and prices it with pre-warmed packs.
Your fleet
Each block is a domain, each square a mailbox. Dashed block: one spare domain resting.
First invoice $459 covers the warmup already done. Ships in 48 hours.
The formula
| Emails needed per month | meetings ÷ reply rate ÷ meeting rate |
| Emails per day | monthly emails ÷ sending days |
| Mailboxes | daily emails ÷ emails per mailbox, rounded up |
| Domains | mailboxes ÷ 3, rounded up, plus 1 spare |
Pricing uses Getlead's public packs (3, 12 or 30 mailboxes, extra mailboxes $7.50-9.50 a month) checked November 2026. Other providers are priced on prewarmedmailboxes.com/pricing.
Questions people ask
How many mailboxes do I need for cold email?
Divide your daily send target by about 30 cold emails per mailbox. For 900 emails a day you need 30 mailboxes. Then divide by 3 to get sending domains (10 here), and keep one spare domain resting.
How many emails do I need to send to book a meeting?
It depends on your list and offer, but a common planning range is a 1-3% reply rate and 20-40% of replies turning into meetings. At 2% replies and 30% meeting conversion you need about 170 emails per meeting.
Why 3 mailboxes per domain?
Reputation is scored largely at the domain level. Spreading volume over more domains means one bad domain only affects a third of a small group, and per-domain volume stays low enough to look like normal business email.