How to Set Up Cold Email Domains That Actually Land in the Inbox

Most cold email campaigns fail before a single email is sent. Here's the complete domain setup checklist that 7-figure agencies use.

Cold email deliverability starts with one thing: your domain infrastructure. Get this wrong and it doesn't matter how good your copy is — you're landing in spam.

Here's the exact setup we recommend, used by agencies doing 10,000+ sends per month.

Why You Need Sending Domains (Not Your Root Domain)

Never send cold email from your main domain (yourcompany.com). If it gets blacklisted, your entire business email goes down with it.

The standard setup is 3–5 sending domains per 1,000 emails/day you want to send. Each domain runs 2–3 inboxes, each sending 30–50 emails/day.

The Domain Setup Checklist

1. Register Domains That Look Legit

Your sending domains need to look like real business variants of your brand. Common patterns:

get-yourcompany.com
yourbrandteam.com
tryyourbrand.com
yourbrandco.com

Avoid hyphens where possible, and always use .com — other TLDs tank deliverability. You can get fresh .com domains with inboxes pre-configured at Warm Inboxes — they even include free domains with inbox purchases.

2. Set Up Your DNS Records

Every sending domain needs three records configured correctly:

SPF Record — tells receiving servers which IPs are allowed to send on your behalf.

v=spf1 include:_spf.google.com ~all

Use the free SPF checker to verify yours is correct.

DKIM — a cryptographic signature that proves your emails haven't been tampered with. Enable this in Google Workspace or Microsoft 365 after domain verification.

DMARC — tells receiving servers what to do when SPF/DKIM fail.

v=DMARC1; p=none; rua=mailto:you@yourdomain.com

Start with p=none (monitor only) and verify with the DMARC checker.

3. Warm Your Inboxes Before Sending

This is where most people kill their campaigns. Sending from a fresh inbox to real prospects = instant spam folder.

Every new inbox needs 2–4 weeks of warming — automated human-like email activity that builds sender reputation with Google and Microsoft's algorithms.

You can buy pre-warmed inboxes directly from Warm Inboxes, which means zero waiting time and you can launch campaigns immediately. They also offer 24/7 WhatsApp support if you need inboxes urgently.

4. Verify Your Setup

Before sending a single email:

✅ Run a deliverability check — tests your actual inbox placement
✅ Check your domain isn't on any blacklists
✅ Use the DNS checker to confirm all records propagated

5. Monitor Domain Expiry

If your sending domain expires mid-campaign, every email bounces. Set calendar reminders or use the domain expiry checker to track all your domains in one place.

How Many Inboxes Do You Actually Need?

Use the Cold Email Volume Calculator — it'll tell you exactly how many domains and inboxes you need based on your target send volume.

As a rough guide: | Daily Volume | Domains Needed | Inboxes Needed | |---|---|---| | 100 emails/day | 1–2 | 3–6 | | 500 emails/day | 4–5 | 12–15 | | 2,000 emails/day | 15–20 | 45–60 | | 10,000 emails/day | 70–100 | 200–300 |

When Infrastructure Burns

Even with perfect setup, inboxes get burned — it happens to everyone. The agencies that survive are the ones with a reliable source to replace infrastructure fast.

Warm Inboxes is used by Agency Velocity, Understory, Mailfirst, B2BScale and many others precisely because of the turnaround speed. Read their reviews here.

If you want an expert eye on your current setup, you can book a deliverability consultation directly.