Introduction
Even the best cold email copy won’t convert if it lands in spam. Deliverability has become the make-or-break factor in outbound sales—and your email infrastructure is the foundation. In this guide, you’ll learn how to set up a reliable, cost-effective, and scalable cold email system that ensures your messages reach the inbox.
1. Why Cold Email Infrastructure Matters
No matter how good your offer is, it won’t work if nobody sees it.
- Spam filters are stricter than ever in 2025
- Gmail, Outlook, and others penalize poor setups instantly
- Even outbound agencies have failed due to bad infrastructure
👉 If your emails are invisible, your revenue is too.
2. What Makes a Good Cold Email Setup?
Your system should be:
- Cost-efficient – doesn’t require huge monthly spend
- Diversified – multiple tools, providers, domains
- Reliable – tools that auto-update with compliance standards
- Scalable – easily add domains and inboxes
- Compliant – SPF, DKIM, DMARC, unsubscribe handling
3. Tools You’ll Need
a) Prime Forge – Domain purchasing & inbox setup
- Centralized platform for buying domains (Google/Microsoft)
- Create mailbox aliases and manage multiple clients
- Supports multiple workspaces
- Suggests smart domain variations (e.g.
trybrand.com, getbrand.net) - Costs: ~$12–20/year per domain, $2.5–3.5/month per mailbox
b) Instantly – Warming up & sending
- Add inboxes to warm-up system
- Track deliverability and health scores
- Configure domain settings, signatures, and custom tracking URLs
- Monitor sender reputation with real-time scoring
4. Domain Diversification Strategy
Don’t put all your emails in one basket:
- Use both Google and Microsoft domains (e.g. 60/40 EU or 70/30 US split)
- Match domain type with recipient’s provider (Google-to-Google, Microsoft-to-Microsoft)
- Use
.com or .net domains where possible - Create 2–3 inboxes per domain, not more—this spreads risk
5. Warm-Up Process: Best Practices
Proper domain warm-up protects reputation and improves inbox placement.
Warm-up checklist:
- Send 3–5 emails/day, slowly increase to 15/day
- Keep warm-up active before and after launch
- Use emulated opens/replies to mimic human behavior
- Set reply rate to ~30%, inbox placement tests = daily send volume
- Add custom tracking domain to reduce spam suspicion
🔁 Example: Sending 300 emails/day? → 15 emails/inbox → Need 20 inboxes across 10 domains
6. Technical Setup Tips
- Always verify SPF, DKIM, DMARC
- Use signature variables to customize at scale
- Configure custom tracking URLs (e.g.
int.brand.com) - Enable read emulation, weekday-only sending, and balanced reply logic
📈 Monitor your health score — aim for 95–100%. If it drops, revisit tracking setup and inbox behavior.
7. Additional Providers for Extra Redundancy
- Mailer/Maildozer: Custom SMTP-based systems for non-Google/Outlook setups
- Helps diversify traffic and reduce platform-level bans
Pro Tip: Keep infrastructure "horizontal"—more domains with fewer inboxes each beats a single overloaded domain.
Final Thoughts: Build It Right or Land in Spam
The technical side of cold email is no longer optional—it's mission-critical.
To recap:
- Set up reliable domains with Prime Forge
- Warm them up gradually with Instantly
- Diversify across providers and domains
- Match recipient platforms
- Follow compliance and technical hygiene
💬 Want to reach the inbox and scale cold outreach? Start by fixing your foundation.
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