How to Warm Up a Domain for Cold Email (Without Hurting Deliverability)

Warm your existing domain and inboxes

Even if you’re already sending cold emails, warming your inboxes helps pad deliverability.

What to do:

Add your current inboxes to a warming tool like Smartlead
Set volume to ~10 emails/day
Set reply rate to 95–100% (most warmers simulate replies for this)

Campaign sending limits:

Keep total outbound volume to ~50 emails/day
→ That’s about 17 new people enrolled per day
This helps maintain a safe domain reputation while warming in the background

Warm a new domain (not a subdomain)

New domains should be warmed gradually before full use.

What to do:

Register a new domain
Add it to Smartlead or a similar warmer with ramp-up enabled
Start with 20–50 total sends/day per inbox
Aim for a 20–40% reply rate in the first week
After one week, increase warm-up volume to 40–50/day

⚠️ Use a completely new domain, not just a subdomain of your main one

Rotate inboxes and swap behavior

To keep your domain healthy long-term:

Rotate the inboxes being used in live campaigns
Rotate the warmers too, don’t keep the same pattern forever
Do a full swap every 2–3 months

✅ Pro tip: forward replies from new inboxes to your main inbox to avoid split conversations

Additional tip: Organize your inbox

Smartlead lets you customize keywords in warm-up emails. You can create filters or folders in Gmail or Outlook to catch these messages and keep them out of your primary inbox view.