How to warm up a new sending domain
Warm a new email sending domain without landing in spam: check you need to, set up DNS, then widen from 30-day engaged subscribers over several weeks.
What this is for
Mailbox providers such as Gmail judge a sending domain partly by its history. A new domain has none, so its first sends are watched closely. Warming means sending small volumes to your most engaged subscribers first and growing slowly, so the first thing Gmail and the others learn about you is that people open your mail. source, checked 28 September 2026
This guide follows Klaviyo's standard warming process for a marketing domain. The same pattern of engaged segments first and slow growth applies to any email platform; only the menu names change.
Time needed and what you need
Time needed: about 6 to 8 weeks. DNS setup takes an afternoon; the rest is two-week stages of sending to wider engagement segments while you watch open, bounce and spam rates.
- Login access to wherever your domain's DNS is managed (Shopify, Cloudflare, GoDaddy or similar)
- Your email platform account with permission to add a sending domain
- Engagement history from your old platform, if you are moving, so you can build engaged segments
- A Google Postmaster Tools account for the domain, to watch your Gmail spam rate
- A campaign calendar for the next two months that you are willing to slow down
The steps
Hold back on flows and big campaigns until step 7. Warming fails most often because someone sends a large promotion in week one.
1. Check whether you need to warm at all
Not every change needs a warm-up. If you are an existing Klaviyo sender moving to a branded domain that is at least 30 days old and has sent email before, Klaviyo says you can skip it. A domain registered in the last 30 days, or one that has never sent email, needs the full process. source, checked 28 September 2026
Transactional and service domains, which carry order confirmations and support replies, usually do not need warming. This guide is about the marketing domain. source, checked 28 September 2026
2. Set up the branded sending subdomain and DNS
In Klaviyo's domain settings, add a branded sending domain on an unused subdomain of your store's domain, such as send.yourstore.com. Klaviyo generates the records; you add them at your DNS host, or let Klaviyo add them for you where it can connect to the provider. Accept the option to add a DMARC record if your domain has none. source, checked 28 September 2026
This matters beyond warming. Gmail treats anyone sending 5,000 or more messages a day to its accounts as a bulk sender, with stricter rules on authentication and unsubscribing, and a branded domain is part of meeting them. source, checked 28 September 2026
3. Build five engagement segments
Create segments of people who opened or clicked in the last 30, 60, 90, 120 and 180 days. If you are moving from another platform, include the open and click history you imported, or these segments will look almost empty. Everyone outside the 180-day segment waits until warming is done. source, checked 28 September 2026
4. Make the first send small and to your best readers
The first campaign goes to the 30-day segment only, and to fewer than 10,000 people. Send something people reliably open: a new arrival, a restock, a story, not a clearance blast. Klaviyo sets a high target for this send and says you will only hit it with a very recent audience. source, checked 28 September 2026
5. Spend weeks 1 and 2 on the 30-day segment
Keep every campaign to the 30-day engaged segment for the first two weeks. If that segment is large, split each send rather than mailing it all at once: batch sending in the campaign's schedule options, or Smart Send Time if you qualify for it. source, checked 28 September 2026
6. Widen the audience in two-week stages
If open rates hold, move to the 60-day segment in weeks 3 and 4, then 90 days, then 120 and 180. Each widening adds people who are a little less keen. If opens fall below Klaviyo's floor, stay where you are and do not widen until they recover. source, checked 28 September 2026
- Weeks 1 to 2: 30-day engaged
- Weeks 3 to 4: 60-day engaged
- Weeks 5 to 6: 90-day engaged
- Then 120-day and 180-day, two weeks each
7. Switch flows on in order, riskiest last
Flows send every day, so they add volume you do not control. Turn on the ones with a strong history first. Klaviyo's guidance for flows without that history: welcome after two weeks of campaigns, abandoned cart after 30 days, browse abandonment later still. source, checked 28 September 2026
Leave winback, re-engagement and sunset flows until warming is finished. They go to your least engaged people by design. source, checked 28 September 2026
8. Watch Gmail's spam rate every week
Add the domain to Google Postmaster Tools and check the spam rate weekly. Gmail sets two lines: a level to stay under and a level never to reach. If you get close to the first, go back to a tighter segment for two weeks. source, checked 28 September 2026
9. Slow down at the first sign of deferrals
If a send starts bouncing or mailbox providers defer messages, cut the volume back before you try anything else. Resume growing slowly once the errors stop. source, checked 28 September 2026
A worked example
For a jewelry brand moving 40,000 subscribers to a new sending domain
Worked example (an invented brand, with invented numbers)
The brand's 30-day engaged segment has 6,500 people, its 60-day segment 11,000, its 90-day segment 16,500 and its 180-day segment 24,000. The other 16,000 subscribers are not mailed during warm-up.
Week 1: a restock email to the 6,500 gets 2,340 opens, a 36% open rate. Week 3: the first send to the 60-day segment gets 2,530 opens from 11,000, which is 23%, so the brand keeps widening. Week 5: the 90-day segment gives 3,135 opens from 16,500, or 19%.
That is under the 20% floor, so the brand stays on the 90-day segment for two more weeks instead of moving to 120 days, and swaps its planned discount email for a new-collection story. The next two sends come back at 22% and 24%, and the ramp continues.
Common mistakes
Sending the whole list a Black Friday email in the first month. A sudden jump from nothing to tens of thousands is exactly what Gmail warns about. source, checked 28 September 2026
Switching every flow on the day the domain is verified. Flows add volume daily, often to people who are not in your engaged segments. Turn them on one at a time, in the order in step 7.
Stopping campaigns during warming and expecting the guidance to wait. If you qualified for Klaviyo's guided warming and then send nothing for 45 days, the notifications are dismissed for good, though the manual process still applies. source, checked 28 September 2026
Reading open rates at face value. Apple Mail Privacy Protection counts automatic loads as opens, so a warming send can look healthier than it is. Watch clicks, bounces and spam complaints alongside opens. source, checked 28 September 2026
Doing this with Tilly
Tilly does not send email or warm domains; it writes into Klaviyo, and Klaviyo does the sending. During a warm-up that is useful: anything Tilly's email marketing agent writes lands in Klaviyo as a draft and waits for your approval, so you choose the segment and the day for every send and keep to the ramp above.
Questions people ask
Do I need to warm up again if I move to a new subdomain later?
Not by hand in Klaviyo. When you replace a branded sending domain you already use, Klaviyo moves your traffic onto the new one gradually when you activate it. source, checked 28 September 2026
What should I do with subscribers outside the 180-day segment?
Leave them out of warming entirely. Once the domain is warm, give them one last chance through a sunset flow and suppress anyone who does not respond. The guide to cleaning an email list covers that step.
Can I keep sending my normal number of campaigns during warm-up?
Often yes, as long as each one goes only to the current engaged segment. What must stay small is the audience, not necessarily the number of sends. If you normally send daily, keep the rhythm and keep the segment tight; see setting an email frequency cap for planning the weeks after.
See this on your own store
Paste your store URL. The first pass takes about a minute and needs no account. Save a card (nothing is charged) and Tilly reads the whole store and works out who buys from you.