How to warm up an email domain
New sending domains have zero reputation with major mailbox providers. Send 200 cold emails on day one and most will land in spam. Warmup ramps volume slowly while generating positive engagement (opens, replies, marks-as-not-spam) to build trust over 4-8 weeks.
This guide covers the day-by-day volume ramp, when to use a warmup service vs manual warmup, and the most common warmup mistakes.
Before you start
- New sending domain or dormant domain
- SPF, DKIM, DMARC configured (warmup without auth = wasted effort)
- Warmup service account (MailReach, Lemwarm, Instantly, Smartlead) OR engaged recipient list for manual warmup
Step-by-step
- 1
Confirm authentication is in place
Before warming up, verify SPF + DKIM + DMARC are all set and passing. Without authentication, warmup engagement signals can't build domain reputation.
- 2
Week 1: 10-30 messages per day, high engagement
Send to recipients who will open and reply. Use a warmup service or send to colleagues / your team. Engagement matters more than volume in week 1.
- 3
Week 2: 30-80 messages per day
Increase by 30-40% week-over-week. Continue engagement-focused sending. Monitor inbox placement via seed-list testing (GlockApps, MailReach inbox tests).
- 4
Weeks 3-4: 80-300 messages per day
Continue 30-40% week-over-week ramp. Start including non-warmup recipients but keep engagement-heavy.
- 5
Weeks 5-6: Start real cold-outbound
Mix warmup volume with real cold outbound. Aim for high reply rates (3-8% on first cold sends) to maintain positive engagement signal.
- 6
Weeks 7-8: Full cold-outbound volume
Drop warmup pool sends to maintenance levels (10-20% of daily volume). Run full cold-outbound at target volume.
- 7
Ongoing: maintenance warmup
Even on warmed domains, keep a baseline of warmup-quality engagement (10-20% of sends) to maintain positive signal during cold-outbound campaigns.
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Troubleshooting
Sustained spam-folder placement past week 4
Either authentication is broken or the cold-list quality is poor (high hard-bounce rate, low engagement). Verify SPF/DKIM/DMARC pass, then re-verify your list and suppress non-engaged recipients.
Sudden deliverability drop after starting cold-outbound
Volume jump too fast. Pause cold outbound for 1 week, increase warmup engagement, then resume at 30% of attempted volume and ramp again.
Reports of recipients marking as spam
Targeting or messaging problem. Tighten ICP, improve personalisation, and lower complaint rate. Sustained complaint rate above 0.3% triggers throttling under bulk-sender rules.
Frequently asked
Can I skip warmup if I bought an old domain?
Risky. Old domains may have residual bad reputation from previous owners. Warm up regardless; the cost is small vs the risk of starting cold-list sending and getting blacklisted.
Do warmup services trick mailbox providers?
Less than they used to. Google and Microsoft have improved at detecting reciprocal warmup networks. The defensive play is engagement on real recipients as soon as your ramp permits.
Does Outsolvi help with warmup?
Indirectly. Outsolvi's confidence-scored opens let you measure real engagement during warmup, which is the signal you're trying to build.
More on email tracking
Glossary terms, comparisons, and feature deep-dives related to this guide.
Nate built Outsolvi after watching every email-tracking tool he had ever used lie to him about opens. Outsolvi runs Tier 1 to 5 confidence scoring on every open, native in Outlook and Gmail, so the number on the dashboard is one a rep can actually act on.
We update these pages when the underlying mechanics change. new mailbox-provider rules, new tracker behavior, new measurement gaps. The dates above are real revisions, not auto-touches.