Setup, Cold email, Infrastructure
How Many Mailboxes and Domains Do You Need for Cold Email?
Divide your daily target by what one warmed mailbox can safely send, then spread the mailboxes over domains at two to three each. Here is the sum, with examples.
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In this article
Divide your daily send target by 40, which is a cautious ceiling for one warmed mailbox, and round up. That is your mailbox count. Then put two to three mailboxes on each domain, so divide the mailbox count by three and round up for your domains. A target of 200 emails a day needs 5 mailboxes and 2 domains.
The formula
- Mailboxes = daily target divided by 40, rounded up. Use 50 only for mailboxes that have sent steadily for a long time.
- Domains = mailboxes divided by 3, rounded up. Use 2 per domain if you want more margin.
- Add one spare mailbox per five, so a paused or unhealthy mailbox does not stop the campaign.
| Daily target | Mailboxes | Domains | With a spare |
|---|---|---|---|
| 50 | 2 | 1 | 3 mailboxes |
| 100 | 3 | 1 | 4 mailboxes, 2 domains |
| 200 | 5 | 2 | 6 mailboxes |
| 400 | 10 | 4 | 12 mailboxes |
The target is not day-one volume
These totals are where you arrive, not where you start. A new mailbox sends 5 to 10 a day at first. Warmerly's campaign ramp opens at 3 per mailbox on day one and adds one per sending day up to a default ceiling of 15, so a new set of mailboxes takes weeks to reach a full target. Plan for that when you set a date for the volume you want.
Why not just send more from fewer mailboxes?
- Filters judge each mailbox and each domain. A spike on one mailbox is easy to see.
- Domain totals compound. Three mailboxes sending 60 each look like 180 a day from one domain.
- A problem on one domain stays on that domain. Spreading across domains limits the damage.
Keep the sums honest
More mailboxes do not fix a poor list or weak targeting. If bounces or complaints are rising, add nothing: pause, clean the list and check authentication. Extra volume of the wrong mail from more domains is how a whole set-up gets listed.
Frequently asked questions
How many mailboxes do I need to send 100 cold emails a day?
At a cautious 40 a day per warmed mailbox, three mailboxes, plus a spare, on one or two domains.
How many mailboxes per domain for cold email?
Two to three is a common rule. It keeps the domain's total daily volume modest and limits the damage if one domain has a problem.
Can a new mailbox send 40 emails a day?
No. A new mailbox starts at 5 to 10 a day and ramps up over weeks. The 40 figure applies to a mailbox that has warmed and sent steadily.
