How many domains and inboxes do you need for cold email?
Start from emails a day, a lead list or a meetings target. Get the inbox and domain count, with each step shown.
- Three ways in
- Runs in your browser
- No email required
Start from the number you have
Inboxes = emails a day ÷ 30 per inbox, rounded up. Domains = inboxes ÷ 3 per domain, rounded up.
The short answer
- Cold email inboxes needed = emails a day ÷ the daily cap per inbox. Sending domains needed = inboxes ÷ inboxes per domain. Round both up.
- At 30 sends per inbox and 3 inboxes per domain, 2,000 cold emails a day need 67 inboxes on 23 domains.
- A 50,000-lead list with three emails each, finished in 8 weeks, is 3,750 emails a day: 125 inboxes on 42 domains.
- The per-inbox cap and inboxes per domain are your own sending rules. Change them in the tool and the answer follows.
The formulas the tool runs
Pick the number you already have. Each path ends in emails a day, and then the same two steps finish it.
- From emails a day: use the figure as it is.
- From a lead list: emails a day = leads × emails per contact ÷ (weeks × 5 working days), rounded up.
- From meetings: positive replies = meetings ÷ booking rate. Replies = positive replies ÷ positive share. Contacts = replies ÷ reply rate. Emails a day = contacts × emails per contact ÷ 21 working days. Each step rounds up.
- Inboxes = emails a day ÷ daily cap per inbox, rounded up.
- Domains = inboxes ÷ inboxes per domain, rounded up.
Emails per contact is the steps you send after replies stop the rest. A four-step sequence where some people reply early lands near 3.5.
Three worked examples
All three use 30 cold sends per inbox a day and 3 inboxes per domain. Swap in your own rules in the tool.
| Starting point | Emails a day | Inboxes | Domains |
|---|---|---|---|
| 2,000 emails a day | 2,000 | 67 | 23 |
| 50,000 leads, 3 emails each, 8 weeks | 150,000 ÷ 40 days = 3,750 | 125 | 42 |
| 10 meetings at 50% booking, 30% positive, 3% reply, 3.5 emails each | 20 → 67 → 2,234 contacts → 7,819 a month ÷ 21 = 373 | 13 | 5 |
Rates in the meetings row are example inputs. Use your own booking, positive-reply and reply rates from a first small campaign.
What to do with a big number
If the inbox count looks large, you have two cheaper levers than buying more. A tighter list raises your reply rate, and a sharper offer raises the share of replies that are positive. Both shrink every later step.
Every extra inbox is one more thing to warm and watch. So size the setup to the target, then protect it with caps you actually enforce.
Let the software hold the caps
Questions
- How many domains do I need to send 2,000 cold emails a day?
- At 30 cold sends per inbox a day and 3 inboxes per domain, you need 67 inboxes on 23 domains. Raise the per-inbox cap to 50 and it drops to 40 inboxes on 14 domains.
- How many domains do I need for 50,000 leads?
- Start from your deadline. Three emails to 50,000 leads over 8 weeks is 3,750 emails a day. At 30 per inbox and 3 inboxes per domain, that's 125 inboxes on 42 domains.
- How many inboxes do I need to send 10,000 cold emails a day?
- At 30 sends per inbox a day, 10,000 emails need 334 inboxes. With 3 inboxes per domain, that's 112 sending domains.
- Why work backwards from meetings?
- Because the meetings target is the only number you were given. Your booking rate, positive-reply share and reply rate turn it into contacts, then emails, then inboxes. A better list or offer shrinks every step after it.
Run the plan on your own inboxes
SalesCrew Core runs cadences on your mailbox pool with daily caps per inbox and per domain, from $299 a month.
Want to see it first? Book a demo