Send 500 emails on day 1 from a fresh domain and you'll land in spam for the next 6 months. There's no shortcut. Every new sending infrastructure has to be warmed.
Here's the 14-day warmup protocol we run on every new account at LeadBound. It's boring. It works. And it's the difference between a 95% inbox-placement rate and a 30% one.
Day 0: Domain setup BEFORE you send anything
Skip this and warming won't save you. The mail providers check authentication on every send. Fail these, and even warmed inboxes drop to spam.
- SPF record: authorize your sending IPs
- DKIM: sign every outgoing message with your domain's private key
- DMARC: set policy to p=quarantine (move to p=reject after 90 days clean)
- MX record: point to a real mailbox provider, not a placeholder
- Custom tracking domain: never use the default smartlead/instantly subdomain
The 14-day ramp curve
The volume curve matters more than the content. Mail providers watch for sudden jumps. Linear growth from day 1 looks suspicious. We use a stepped curve that mimics organic growth.
- Days 1–3: 20 sends/day per inbox, internal warmup only
- Days 4–7: 40 sends/day, mix of warmup + real campaign at 20/day
- Days 8–11: 80 sends/day, real campaign at 60/day
- Days 12–14: 120 sends/day per inbox, production volume
Content during warmup
Your warmup tool sends auto-generated messages to other warmup pools. That's fine for technical reputation, but the messages are easy for spam filters to flag.
Best practice: mix warmup auto-sends with REAL outreach during days 4–14. The real opens and replies build legitimacy faster than any synthetic warmup loop.
Deliverability checks at every stage
Run these checks daily during warmup. If any one fails, pause sending and fix before resuming.
- Mail-tester.com score: ≥ 9/10 every send
- Postmaster Tools (Google): domain reputation "High"
- Smartlead inbox placement test: ≥ 80% to Primary
- Bounce rate: < 3% (anything higher = bad list, not infrastructure)
Red flags to watch for
Inbox placement dropping mid-warmup usually means one of three things: list quality, content, or volume jump. Diagnose in that order.
If you see a 10%+ drop in opens overnight, stop everything and run a fresh deliverability test. Catching a reputation drop early lets you recover; missing it for a week can mean a 90-day rebuild.
- Auth records (SPF, DKIM, DMARC, MX) must be set BEFORE the first send
- Ramp volume in steps, not linearly. Providers watch for sudden jumps
- Mix warmup auto-sends with real outreach starting day 4 for legitimacy
- Run deliverability checks daily; catch reputation drops within 24 hours
