How long should you warm up a new cold email domain?
The short answer
Warm a new sending domain for at least 21 days before the first live cold email. During those three weeks the inboxes send and receive small, rising volumes so mailbox providers learn to trust the domain. Skip it, and your first campaign can land in spam on a domain that carries your company's name.
Why does a new domain need warming at all?
Mailbox providers judge a domain by its sending history, and a new domain has none.
Gmail and Outlook decide where an email lands partly from the sending domain's track record. A domain registered last week with no history looks the same as one set up to spam.
Warmup builds that record. The inboxes send a small number of emails a day, receive replies, and grow volume slowly, so by the first campaign the domain has weeks of normal behavior behind it.
Why 21 days, and not one or two weeks?
Twenty-one days is the floor we hold on every domain, because shorter ramps cost more than they save.
A week of warmup leaves a thin history. A thin history followed by a jump to campaign volume is exactly the pattern spam filters watch for.
We treat 21 days as a hard minimum. A client deadline does not shorten it, because the domain at risk carries the client's name.
What happens during the warmup weeks?
The inboxes send and receive at low, rising volume while the list and the copy get built.
None of that time sits idle. Warmup runs in the background while the rest of the campaign comes together, which is why the first live email can go out in week four.
- SPF, DKIM and DMARC records set up and checked on every sending domain
- Each inbox sends a small daily volume that rises over the three weeks
- Replies during warmup build a record of real engagement
- The buyer list is built and every address verified in parallel
- The campaign copy is written and approved before the first send
Should you send cold email from your main company domain?
No. Send from separate domains so your main domain's reputation is never at risk.
Cold email draws more spam complaints than everyday business email. If your main domain takes that hit, invoices, proposals and client emails can start landing in spam too.
Separate sending domains, registered in your company's name and pointing back to your website, keep the risk contained. We set those up for every client, and they stay the client's.
How do you know a domain is ready to send?
When it has at least 21 days of steady history, passing DNS records, and a verified list waiting.
We check three things before a domain goes live: the warmup history, SPF, DKIM and DMARC all passing, and a list verified well enough that the first sends do not bounce.
After launch, volume still rises gradually. A domain that jumps from warmup straight to full volume throws away the trust it just earned.
Frequently asked questions
Can you warm up a domain faster than 21 days?
Some services advertise shorter warmups. We do not run them, because the risk lands on a domain that carries your name, and a burned domain can take months to recover.
Does an old domain still need warmup?
Yes, if it has never sent cold email. Age helps, but sending history is what mailbox providers trust.
How many inboxes should each sending domain have?
We run two or three inboxes per sending domain and keep each inbox's daily volume low. More volume comes from more domains and inboxes, never from pushing one inbox harder.
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