How do I warm up (or rewarm) my email domain?
Domain warming is how you build trust with mailbox providers like Gmail, Outlook, and Yahoo before sending at full volume. Whether you're launching a new domain, switching platforms, or returning after a sending pause, skipping this process risks landing in spam, or permanently damaging your domain reputation. Follow these steps to warm up safely.
Step 1: Determine your starting point
Not all warm-ups are the same. Your approach depends on your situation:
Existing active domain (platform switch or long pause) Your domain already has a sending history, so you don't need to start from zero. However, mailbox providers will detect infrastructure changes like a new IP pool or different sending patterns. A shorter warm-up of 2–3 weeks is typically sufficient.
Brand-new domain Mailbox providers treat new domains with extreme suspicion. Best practice: register the domain, configure your DNS records (SPF, DKIM, and DMARC), and let it "age" for at least 30 days before sending any emails. Warming then requires a very slow, deliberate ramp.
Before beginning either type of warm-up, confirm that your authentication is fully configured. Warming without SPF, DKIM, and DMARC in place will not establish trust.
Step 2: Define your audience segments
The key to warming is always starting with your most engaged contacts and expanding outward. Providers reward you when recipients open, click, and engage, so you want to send first to the people most likely to do exactly that.
Here's a recommended prioritization (adjust based on your list):
| Priority | Segment | Risk Level |
|---|---|---|
| 1 | Clicked in the last 30 days | Lowest — start here |
| 2 | Opened in the last 15–30 days | Low |
| 3 | Opened in the last 60–90 days | Moderate — introduce gradually |
| 4 | No activity beyond 90 days | High — use sparingly or suppress |
You know your list better than anyone. Use this as a guide and adjust based on your organization's engagement patterns.
Step 3: Start small and send real campaigns
Begin with a small send; hundreds to low thousands of contacts, depending on your normal volume, to your most engaged segment.
Key rules for this phase:
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Send real, engaging campaigns, not test emails. Mailbox providers prefer realistic traffic.
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Use your normal content and sending cadence; don't create a "warming-only" message.
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Open and click rates during warming should be higher than usual, because you're sending to your best contacts first. Use this as your baseline.
Step 4: Ramp up gradually
After each send, review your engagement metrics before expanding to the next segment.
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At most, double your send size with each step.
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Only expand when engagement is stable; open rates are healthy and bounce rates are low.
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If bounce rates climb or engagement drops, hold your current volume or pull back before continuing.
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A proper warm-up takes at least 30 days. There are no shortcuts; attempting to rush will raise red flags with providers.
Step 5: Troubleshoot if issues arise
If you see problems during warming, act quickly:
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Drop in open rate or engagement → Pull back to a smaller, more engaged segment. Check authentication and content.
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Spike in bounces → Pause. Run a list hygiene check. Don't continue until you understand the source.
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Mail landing in spam → Confirm your authentication records are in place and correctly aligned. Review your content for spam triggers. Consider contacting Bonterra Support.
What else do you need help with?
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Navigate back to the Email Deliverability Index.
How do I warm up a new sending domain in Targeted Email? | How long should domain warming take in EveryAction? | Why is my EveryAction email going to spam after switching platforms? | How do I build a warm-up audience segment in Targeted Email? | How do I ramp up sending volume safely in Targeted Email? | What should I do if bounce rates spike during domain warming? | Do I need to warm up my domain after a sending pause?