Buy the domain weeks before you need it. Publish SPF, DKIM and DMARC and confirm they resolve rather than merely exist. Then ramp from two to five messages a day up to eight to ten over two to three weeks, counting warm-up traffic inside that daily number.
Published by emailcampaign.ai, which provisions and warms domains as part of its service. The schedule below is the one we run.
Before the first message
Register early. Domain age is a weak signal on its own but a free one. A domain bought six weeks ago and warmed for three is in a better position than one bought and warmed the same week.
Publish authentication and verify it evaluates. This is the step most often done badly, because the records look correct while failing. Two SPF records on one host is a permanent error, not a merge. An include chain past ten DNS lookups is also a permanent error, and include:_spf.google.com alone is four of those ten. On Microsoft 365 the DKIM CNAME target contains a per-tenant value, so a record copied from a guide resolves to nothing and signing never turns on. Checking the full tree takes about thirty seconds.
Set up the mailbox properly. A real display name, a signature with a postal address, and a profile photo if the provider supports one. A mailbox that looks unfinished sends mail that looks unfinished.
The ramp, week by week
| Period | Daily total | Composition |
|---|---|---|
| Days 1 to 3 | 2 to 5 | Warm-up only. No campaign traffic |
| Week 1 | 5 to 8 | Warm-up only. A bounce spike here means DNS or the mailbox, not volume |
| Week 2 | 8 to 12 | First campaign sends, two or three, inside the same cap |
| Week 3 | Full cap | Split between warm-up maintenance and campaigns |
| Steady state | 8 to 10 campaign sends | Indefinitely. More volume comes from more mailboxes |
Every number in that table is the mailbox’s total outbound, which is the point of the next section.
The mistake that wastes the whole three weeks
Warm-up tools and campaign tools usually report separately, so it is easy to read "warm-up at 20 a day" and "campaign at 30 a day" as two independent numbers. The mailbox does not work that way and neither does the receiver. That mailbox is sending fifty a day.
A team that finishes a two week warm-up, starts campaigns at ten a day on top of warm-up still running at eight, and then wonders why placement fell has not run a three week warm-up. They have run a mailbox at eighteen a day in week three, from a domain with no history.
Count one number per mailbox, and make every tool report into it.
Warm-up does not end
After the ramp it drops to a maintenance level and continues for as long as the mailbox sends. A mailbox whose only traffic is outbound cold email looks different from one having conversations, and maintenance traffic is what keeps that from being the whole picture.
Good warm-up traffic gets opened, replied to, and rescued from junk when it lands there, because the rescue is the signal that teaches the filter. It should also never reach your own working inbox, or your reply metrics become fiction.
A new mailbox on an established domain
Shorter, often about a week, because the domain already carries history. The mailbox still needs its own, so start it at the floor rather than dropping it straight into the fleet’s cap.
Where the volume actually comes from
Eight to ten a day per mailbox is far below what Google and Microsoft publish as limits, and deliberately so: a published limit describes where the provider stops you, not where it starts distrusting you. Three hundred sends a day means thirty mailboxes, not three mailboxes working harder. Plan the fleet, and stagger the warm-up starts so they do not all finish on the same day.
Questions, answered straight
- How do I warm up a new email domain?
- Register it well before you need it, publish SPF, DKIM and DMARC and confirm they resolve, then ramp sending from a handful of messages a day to the mailbox's working cap over two to three weeks. Warm-up traffic and campaign traffic must share the same daily allowance.
- How long does domain warm-up take?
- Two to three weeks to reach a working cap of eight to ten cold sends per mailbox per day. The clock starts when sending starts, not when the domain is registered, so buying domains early lets them age in parallel.
- What is the most common warm-up mistake?
- Counting warm-up and campaign traffic separately. A mailbox warming at twenty a day that also sends thirty campaign emails is sending fifty from a mailbox with no history. It is not warming, it is being pushed past what its history supports.
- Do I need to warm up the domain or the mailbox?
- Both, and they warm together. Reputation attaches to the domain and to each sending mailbox, and the mailbox is the thing sending, so ramping each mailbox is what builds the domain's history too.
- Can I skip warm-up if I send small volumes?
- A brand new domain with no history is treated with suspicion even at low volume, so some ramp is always sensible. What you can shorten is a new mailbox on a domain that is already sending, which often needs about a week rather than three.
Published 20 September 2026. Updated 20 September 2026. Written by the team that runs the infrastructure; numbers come from the platform's own provisioning and sending, and from the providers' published documentation at the time of writing.