Plan the fleet
How it works
Capacity
Target × (1 + spare) ÷ sends per inbox gives inboxes; ÷ inboxes per domain gives domains. Both round up.
Cost
Inbox licences per month, domains amortised, the sending tool. Year one adds the domain generations a rotation schedule needs.
Calendar
DNS and authentication, provisioning, warmup, then a first campaign at a quarter volume — dated from today.
Sensitivity
The same target at neighbouring ratios, so you can see what a couple more sends per inbox actually saves — and costs.
The two ratios that decide everything
Sends per inbox per day and inboxes per domain. Everything else in the plan is arithmetic on those two. Twenty-five sends a day is what a warmed Google Workspace inbox sustains for cold traffic month after month; fifty works for a fortnight and then the domain's reputation goes with it. Three inboxes per domain keeps the blast radius small — when one inbox draws a complaint, it takes two others with it, not ten. The defaults are those numbers, and the sensitivity table shows what happens when you push them.
Why spare capacity is not optional
A fleet at exactly its target has no room for a domain that needs to rest, an inbox that gets disconnected, or a week where replies are high and the tool throttles sends. Twenty percent spare is the difference between hitting the number every day and hitting it most days. It also means warmup traffic, which every inbox should keep running, does not eat into campaign volume.
Reading the cost
Inbox licences are most of the monthly figure, which is why the price per inbox matters far more than the price per domain. The default here is what I charge as a Workspace reseller; Google's list price is seven dollars and changes the total by two-thirds. Domains are cheap and should be treated as consumable — the lifespan input and the year-one figure assume you retire and replace them in rotation rather than trying to nurse a burned domain back.
The calendar is the honest part
Everyone wants to send tomorrow. Buying domains, moving DNS, publishing authentication, provisioning inboxes, connecting them and warming them takes two to three weeks for a fleet of any size, and the first campaign should run at a quarter of target for another week. Starting a fleet at full volume on day three is the most expensive mistake in cold email, and the calendar exists so the date is in front of whoever is asking for it.
Frequently asked questions
How many inboxes do I need to send 1,000 cold emails a day?
At 25 sends per inbox with 20% spare, 48 inboxes across 16 domains. At 50 per inbox you need half as many and the domains last a fraction as long.
How many inboxes per domain?
Two or three. More concentrates risk: a complaint on one inbox affects the domain's reputation and every other inbox on it.
How many emails can one inbox send per day?
Google Workspace allows 2,000. For cold email, 25–30 is the sustainable figure. The limit is reputation, not the provider's cap.
What does the year-one cost include?
Twelve months of inbox licences and tool, plus enough domain purchases to replace the fleet on the rotation schedule you set. It does not include list data or labour.
How long before I can send at full volume?
About three weeks from purchase: a few days for DNS and provisioning, two weeks of warmup, then a week at reduced volume. The calendar in the results dates each step from today.
Last reviewed
What to run next
The checks that most often follow this one.
More in this category
Guides that go deeper
When the tools tell you something is wrong
The diagnostics here are free and always will be. When the fix is bigger than a DNS record, this is the work I do.
Deliverability rescue
Mail landing in spam, replies gone quiet, or a domain suddenly blocked. I find the actual cause rather than guessing, and fix it.
- Authentication and alignment failures
- Blocklist delistings and reputation repair
- Gateway and filter-level blocks
- A written report on what broke and why
Email & sending infrastructure
Sending domains, inboxes, authentication and warmup, built to survive volume instead of burning down in a month.
- Domain and inbox fleets at any scale
- SPF, DKIM, DMARC and tracking domains
- Google Workspace — Silver Partner
- Handover documentation you actually own
Domain, DNS & migration
Changing registrar, mail provider or host without a day of downtime or a week of mail silently failing.
- Registrar and nameserver moves
- Workspace and Microsoft 365 migrations
- MX, SSL and subdomain cutover
- Staged rollout with rollback at every step
Monitoring & retainer
Infrastructure drifts. Records get edited, certificates expire, domains get listed. Ongoing eyes on the fleet.
- Scheduled checks across every domain
- Alerts before your clients notice
- Monthly reporting
- Priority response when something breaks
Start with a call
Bring a domain and the symptom. I will tell you what is actually wrong and whether you need me at all — plenty of people leave that call able to fix it themselves.
Thirty minutes, no pitch
We will run the checks together on your actual domains, and you will leave knowing what is broken, what it takes to fix, and what it should cost. If that is a job you can do in-house, I will say so.