How to Warm Up a New Email Domain in Klaviyo

You just set up your branded sending domain in Klaviyo. You authenticated your DNS records. SPF, DKIM, DMARC — all green. You're ready to send.

So you blast your entire list of 50,000 subscribers on day one.

And your emails go straight to spam.

This is the most common deliverability mistake we see at GOSH Digital, and it's almost always preventable. New sending domains don't have reputation yet. Email providers (Gmail, Yahoo, Outlook) don't know if you're a legitimate brand or a spammer. They need proof. And the way you prove it is through a warm-up process.

Let me show you exactly how to do it.

Why Warm-Up Matters

Email providers assign a reputation score to every sending domain and IP address. This score determines where your emails land: inbox, promotions tab, or spam.

A brand new domain has zero reputation. Zero doesn't mean neutral — it means suspicious. The email providers think: "We've never seen this domain before. We don't know if people want email from it. Let's be cautious and filter it."

If you send a large volume from a zero-reputation domain, the providers see a sudden surge of email from an unknown sender. That pattern matches spammer behavior. So they filter you aggressively.

Warm-up is the process of gradually increasing your sending volume while maintaining high engagement rates. You're essentially telling Gmail and Yahoo: "Look, real people are opening and clicking my emails. I'm not spam. Let me through."

Before You Start: The Checklist

Before sending a single email from your new domain, verify:

DNS authentication is complete. In Klaviyo, go to Settings, then Domains. Your branded sending domain should show green checkmarks for SPF, DKIM, and DMARC. If any of these are yellow or red, fix them first. Sending without proper authentication is like showing up to airport security without an ID.

DMARC policy is set. At minimum, have a DMARC record of v=DMARC1; p=none; on your domain. This tells email providers you've set up authentication. You can tighten the policy later.

Your list is clean. Do NOT warm up a domain with a dirty list. Remove bounces, spam complaints, and unengaged subscribers before you start. If your list hasn't been emailed in 6+ months, it's going to have dead addresses that bounce. High bounce rates during warm-up will tank your reputation before it starts.

Your content is ready. The emails you send during warm-up need to be your best content. High-quality subject lines, relevant content, clear value. You need opens and clicks. Generic "Hey, we exist" emails won't cut it.

The Warm-Up Schedule

Here's the schedule we use for clients moving to Klaviyo or setting up a new sending domain. This assumes a total list of 20,000-50,000 subscribers.

Week 1: Your Most Engaged Subscribers Only

• Day 1-2: Send to your top 500 most engaged subscribers (opened or clicked in the last 30 days)
• Day 3-4: Expand to top 1,000
• Day 5-7: Expand to top 2,500

These are the people most likely to open, click, and not mark you as spam. Their engagement signals tell email providers your domain is legitimate.

Week 2: Expanding the Circle

• Day 8-9: Send to top 5,000 (engaged in last 60 days)
• Day 10-11: Send to top 7,500
• Day 12-14: Send to top 10,000

Week 3: Broadening Further

• Day 15-17: Send to 15,000 (engaged in last 90 days)
• Day 18-21: Send to 20,000-25,000

Week 4: Full Volume

• Day 22-25: Send to 30,000-40,000
• Day 26-28: Full list (excluding suppressed, bounced, and deeply unengaged)

If your list is larger than 50,000, extend this to 6-8 weeks. The principle stays the same: start small with your most engaged, gradually expand.

Building Warm-Up Segments in Klaviyo

You need segments for each stage of the warm-up. Here's how to build them:

Segment: Warm-Up Tier 1 (500 most engaged)

• Condition: "What someone has done" then "Opened Email" at least 3 times in the last 30 days
• AND "What someone has done" then "Clicked Email" at least 1 time in the last 30 days

Segment: Warm-Up Tier 2 (2,500 engaged)

• Condition: "Opened Email" at least 2 times in the last 60 days

Segment: Warm-Up Tier 3 (10,000 engaged)

• Condition: "Opened Email" at least 1 time in the last 90 days

Segment: Warm-Up Tier 4 (full engaged list)

• Condition: "Opened Email" at least 1 time in the last 180 days
• OR "Clicked Email" at least 1 time in the last 180 days

Avoid sending to anyone who hasn't engaged in over 180 days during the warm-up period. After warm-up is complete and your reputation is established, you can cautiously test re-engagement campaigns to older subscribers.

What to Send During Warm-Up

The content matters. During warm-up, you want to maximize engagement (opens and clicks) and minimize negative signals (spam complaints and bounces).

Best content for warm-up:

• Exclusive offers or early access (incentivizes opens and clicks)
• Top-performing previous campaigns (you already know these get engagement)
• Educational content that's genuinely useful (guides, tips, how-tos)
• Product launches or new arrivals (curiosity-driven opens)

Avoid during warm-up:

• Purely promotional "buy now" emails with no value
• Win-back campaigns to disengaged subscribers
• Anything experimental or untested
• Massive image-heavy emails with no text (some spam filters flag these)

Subject lines should be clear and compelling. Avoid spam trigger words (free, guarantee, act now, limited time) more strictly during warm-up than usual. Once your reputation is established, you can be more flexible.

Monitoring During Warm-Up

Check these metrics daily during the warm-up period:

Open rate. Should be above 30% for Tier 1, above 25% for Tier 2, above 20% for Tier 3. If open rates drop below 15% at any tier, stop expanding and figure out why.

Bounce rate. Should be below 1%. Above 2% is a problem. Above 5% means your list has hygiene issues — stop sending and clean the list.

Spam complaint rate. Should be below 0.1% (1 complaint per 1,000 emails). If it's above 0.3%, pause and investigate.

Unsubscribe rate. Normal is 0.2-0.5%. Above 1% during warm-up means your content or targeting is off.

Inbox placement. Use a tool like GlockApps or Mailreach to test inbox placement at Gmail, Yahoo, and Outlook. If you're landing in spam at any major provider, slow down and adjust.

What to Do If Things Go Wrong

Emails Are Landing in Gmail Spam

Gmail is the strictest during warm-up. If you see inbox placement dropping at Gmail:

1. Reduce volume immediately (go back one tier)
2. Send only to Gmail-specific engaged subscribers
3. Ask engaged subscribers to move your email from spam to inbox (this signals Gmail that it's wanted)
4. Check your email content — is it heavy on images with little text? Does it have suspicious links?
5. Verify your DMARC, SPF, and DKIM again

Bounce Rate Spiking

High bounce rates mean your list has bad addresses. This could be:

• Old addresses that have been deactivated
• Typos in email addresses (gmal.com instead of gmail.com)
• Spam traps (recycled email addresses that ISPs use to catch spammers)

Stop sending. Clean the list using an email verification service (ZeroBounce, NeverBounce, BriteVerify). Remove all hard bounces and risky addresses. Resume warm-up with the cleaned list.

Spam Complaints Rising

People are marking your email as spam. This is the most damaging signal. Possible causes:

• People don't recognize your brand (new domain looks different from what they subscribed to)
• You're emailing people who didn't opt in
• Your content isn't what they expected

Fix: Make sure your "From name" and "From email" are recognizable. Include your brand name prominently. Only email people who actively opted in.

Warm-Up for Migrating Platforms

If you're migrating from Mailchimp, Sendlane, or another platform to Klaviyo, the warm-up still applies. Even if you've been emailing your list for years, you're sending from a new infrastructure. The receiving email providers see a new sender.

The migration warm-up is usually faster (2-3 weeks instead of 4) because your list is already engaged and expecting your emails. But don't skip it. We've seen brands lose months of deliverability by going full blast on day one of a migration.

After Warm-Up: Maintaining Reputation

Warm-up isn't a one-time event. Your domain reputation is ongoing. To maintain it:

• Keep bounce rates below 1%
• Keep spam complaints below 0.1%
• Regularly clean your list (remove unengaged subscribers every 90-180 days)
• Don't suddenly double your sending volume (gradual increases always)
• Monitor deliverability metrics weekly
• Send consistently — long gaps followed by sudden volume spikes can hurt reputation

The Bottom Line

Domain warm-up is boring. It's not exciting. Nobody wants to wait four weeks to send to their full list. But the alternative is landing in spam for months and losing revenue while you dig yourself out.

Do it right the first time. Build the segments. Follow the schedule. Monitor the metrics. Your future self (and your email revenue) will thank you.

If you're migrating to Klaviyo or setting up a new domain and want someone to handle the warm-up process, talk to our team. We've done this dozens of times and we know exactly how to protect your deliverability while ramping up revenue.