One of the biggest mistakes in cold emailing is sending bulk emails from a new or inactive domain without warming it up. In 2025, email deliverability is stricter than ever. Warming up your domain builds sender reputation and keeps you out of the spam folder.
🔹 What is Email Warm-Up?
Email warm-up is the gradual process of increasing your email sending volume and activity to build a positive reputation with Internet Service Providers (ISPs) like Gmail, Outlook, etc.
🔹 Why is Warming Up Important?
Increases your chances of landing in the inbox
Builds trust with email providers
Prevents blacklisting or email bans
Improves deliverability and response rates
🔹 How to Warm Up Your Email Domain Step-by-Step
Step 1: Set Up Proper Authentication
Configure SPF, DKIM, and DMARC records
Use a business domain (not free ones like Gmail/Yahoo)
Step 2: Start Small
Send 10–20 emails per day manually at first
Focus on high-quality, personal emails
Step 3: Gradually Increase Volume
Increase send rate slowly over 2–4 weeks
Add 10–20 more emails per day as engagement improves
Step 4: Engage with Real Users
Ask contacts to reply, mark as important, and avoid deleting without opening
This helps build a "positive" signal
Step 5: Monitor Deliverability
Use tools like Mail-Tester, GlockApps, or Warmbox
Track open rates and spam complaints
Step 6: Use a Dedicated Sending Domain
Consider using a subdomain (e.g., outreach.yourdomain.com)
Helps protect your main domain reputation
🔹 Tools to Help with Domain Warm-Up
Mailwarm
Lemwarm (by Lemlist)
Warmbox
Folderly
✅ Summary: Warm-Up Best Practices
Never start cold email from a fresh domain
Authenticate your email domain properly
Increase volume slowly with real interaction
Use warm-up tools to automate and monitor the process
Conclusion:
Before launching a cold outreach campaign in 2025, warming up your email domain is non-negotiable. A proper warm-up ensures your emails reach the inbox and helps you build lasting sender credibility.