How to Warm Up a New Email Domain
Email domain warm-up is the process of gradually building trust with mailbox providers by slowly increasing sending volume while maintaining strong engagement and low complaint rates. Rather than sending your full email list on day one, you start with your most engaged subscribers and increase volume over several weeks. This helps establish a positive sender reputation before scaling up.
So why do new domains need warming up?
Because a new domain has no sending history. ISPs evaluate factors such as sending consistency, email authentication, open rates, CTR, spam complaints, and bounce rates. When a brand-new domain suddenly sends a large volume of emails, it can resemble spam activity. Even legitimate businesses can experience poor inbox placement if they skip the warm-up process.
How to Warm Up a New Email Domain
1. Set Up Email Authentication
Before sending your first email, configure proper email authentication. At a minimum, your domain should have SPF, DKIM, and DMARC. These records verify that your emails are legitimate and help protect your domain from spoofing. Many email providers recommend starting with DMARC p=none (monitor only, no action taken) while monitoring reports, before moving to p=quarantine (route failing messages to spam), and eventually p=reject (block failing messages entirely) once everything is working correctly.
2. Start With Your Most Engaged Subscribers
Don’t email your entire subscriber list from day one. Instead, begin with subscribers who have recently opened or clicked emails, made purchases, or otherwise actively engaged with your brand. Positive engagement sends strong trust signals to mailbox providers and helps build your sender reputation much faster.
3. Gradually Increase Send Volume
A successful warm-up focuses on steady, predictable growth. For example, instead of immediately sending 50,000 emails, you might start with just 5% if your usual email list, and increase send volume every few days if engagement metrics remain healthy. Then, continue expanding until your new domain can handle your entire email list.
The exact numbers depend on your typical email volume, but consistency is more important than speed. Avoid sudden spikes in sending volume, as these can negatively impact deliverability.
4. Continue Using Your Old Domain During the Transition
If you’re rebranding, don’t switch domains overnight. A gradual migration is generally much safer than moving all email traffic to the new domain at once.
A typical approach looks like this:
- Continue sending most campaigns from your existing domain.
- Begin sending selected emails from the new domain.
- Slowly shift more campaigns as the new domain builds reputation.
- Retire the old domain only after the new one has established consistent inbox placement.
5. Choose Low-Risk Emails First
During the first few weeks, send emails that are likely to receive positive engagement. These could include welcome emails, rebrand announcements, account confirmations, customer service follow-ups, preference center confirmations, and newsletters sent to highly engaged subscribers. Avoid sending to inactive subscribers or low-engagement segments until your domain has built a solid reputation.
Also, transactional emails often generate excellent engagement because recipients expect them. These could include order confirmations, shipping notifications, password resets, and account verification emails. Many businesses warm up their domain using these messages before gradually introducing marketing campaigns.
If your transactional emails use a different subdomain than your marketing emails, remember that each sending domain or subdomain develops its own reputation. In many cases, both should be warmed up independently.
Finally, email warm-up isn’t done when you hit send. Keep an eye on engagement metrics such as open rate, CTR, bounce rate, spam complaint rate, and unsubscribe rate. If complaints or bounces begin increasing, pause your volume increases until performance stabilizes.