Domain Warming: Domain Warming Guide: Build Sender Reputation from Zero
A complete domain warming schedule — day-by-day send volumes, what to monitor, and when you are ready for full volume.
Why domain warming exists
A new domain has no sending history. Inbox providers use historical patterns to determine inbox vs spam placement. Sending thousands of emails from a new domain immediately triggers spam filters — the provider assumes you're a spammer because legitimate senders don't start at volume.
Warming builds reputation gradually by demonstrating consistent, low-complaint sending over 4-6 weeks. Each week, you send slightly more emails and prove to inbox providers that your domain is trustworthy.
Think of it like building credit. You can't get a mortgage without a credit history. You can't get inbox placement without a sending history. Domain warming is how you build that history from zero.
The 6-week warming schedule
Week 1: 50 emails per day. Send only to your most engaged contacts — people who have opened and clicked your emails before. These are your warmest contacts and most likely to engage.
Week 2: 200 emails per day. Expand to your full engaged list. Monitor open rates (target: 30%+) and bounce rates (target: under 2%). If either metric looks bad, pause and investigate before continuing.
Week 3: 500 emails per day. Start mixing in newer contacts. By now your domain should have enough history to reach the inbox consistently. If you're still seeing spam folder placement, check your authentication records.
Week 4: 1,000 emails per day. Scale confidently if previous weeks showed good metrics. Week 5: 3,000 emails per day. Week 6+: scale to your target volume. SpaceCRM's warmup automates this entire schedule.
Metrics to monitor during warming
Watch: inbox placement rate (target 95%+), spam folder rate (keep below 2%), open rate (above 20%), complaint rate (below 0.1%). These four metrics tell you whether your reputation is building or deteriorating.
If spam placement exceeds 5%, pause immediately. Review authentication setup, list quality, and email content before resuming. Continuing to send while spam rates are high damages your reputation further.
Track deliverability daily during the first 4 weeks. SpaceCRM's warmup dashboard shows real-time inbox placement across Gmail, Outlook, and Yahoo so you can catch issues before they become reputation damage.
Common mistakes that reset reputation
Mistake 1: Scaling too fast. Jumping from 100 to 1,000 emails per day in week 2 triggers spam filters. Follow the schedule — patience pays off with long-term deliverability.
Mistake 2: Sending to unverified lists during warmup. One batch of invalid addresses can destroy weeks of reputation building. Verify every contact before sending.
Mistake 3: Sharing warmup volume with marketing emails. If your transactional and marketing emails consume the same warmup budget, your cold outreach deliverability suffers. Use separate domains for separate use cases.
When you're ready for full volume
You're ready when inbox placement stays above 95% for 2 consecutive weeks at your target volume. If placement drops when you increase volume, you've scaled too fast — step back and resume the schedule.
Monitor weekly for the first 3 months after warming. Reputation can deteriorate suddenly if you send a bad campaign, hit a spam trap, or get complaint rates above 0.1%. Catch issues early and your domain stays healthy.
SpaceCRM's domain warmup handles the entire process automatically — from initial warming through ongoing reputation monitoring. Start with the free tier to test deliverability with your own domains.