Cold Email Volume Calculator

How many mailboxes do you need

Target

• Emails per sending day
• Sending days per week

Sending limits

• Sends per mailbox per day: 30 to 50 is the usual safe band. Lower it for a brand new domain.
• Mailboxes per domain: Two or three keeps one bad mailbox from taking the domain with it.
• Warmup weeks: Pre-warmed mailboxes shorten this. New domains should not.

Costs

• Cost per mailbox per month: $
• Cost per domain per year: $

Your list

• Leads to contact
• Emails per lead
• Steps in the sequence, including the first email.

Mailboxes needed: 34
1,000 ÷ 30 per mailbox
Sending domains: 12
34 mailboxes ÷ 3 per domain
Monthly capacity: 21,650 emails
5 days a week
Running cost: $102/month
Mailbox seats only
First month: $246
Seats plus domain registration

Warmup ramp

A new mailbox that opens at full volume gets filtered. This is the schedule to reach your target, and the earliest week you can actually send it.

Working through your list

• Emails to send: 60,000
• 20,000 leads × 3 steps
• Time to finish: 12.0 weeks
• Plus 3 weeks of warmup first

The arithmetic

• Mailboxes: ceil(1000 ÷ 30) = 34
• Domains: ceil(34 ÷ 3) = 12
• Monthly capacity: 1000 × 5 × 4.33 = 21,650
• First month cost: (34 × $3) + (12 × $12) = $246

Volume is an infrastructure problem

Everyone starts with a number of emails they want out the door each day and then discovers that number is not a setting, it is a build. Mailbox providers cap what one address can send before it looks automated, so daily volume is really a question of how many mailboxes you are prepared to run, across how many domains, and how many weeks of warmup you can wait through first.

Why 30 to 50 a day and not 500

The limit is behavioural, not technical. A mailbox that sends five hundred near-identical messages a day to people who never wrote first does not look like a person, and filtering reacts to that pattern rather than to your content. Thirty to fifty is where most operators settle. New domains should start lower, around ten to fifteen, and climb.

Never your main domain, and rarely one domain

Cold outreach belongs on separate sending domains, because reputation damage is permanent and you cannot afford it on the domain your invoices go out from. Spreading mailboxes two or three to a domain also contains the blast radius: one flagged mailbox costs you a third of a domain rather than all of your capacity.

Warmup is the part people cut and regret

A new mailbox needs a couple of weeks of gradually rising volume before it can carry its full load. Skipping it is the single most common reason a technically perfect setup lands in spam from day one. Plan the ramp into your timeline, or buy pre-warmed mailboxes and start at a lower ceiling anyway.

Questions

How many emails can one mailbox really send per day?

How many mailboxes should I put on one domain?

Can I use my company domain?

Does the warmup have to be three weeks?

Is any of this sent anywhere?

We already know your next customer

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