What is IP/domain warming after migration?

After migrating to a new ESP with new IPs, you need to warm those IPs before sending at full volume. Warming establishes reputation through demonstrated good behavior.

• Why warming is necessary:
• New IPs have no history; mailbox providers are suspicious
• Sudden high volume from unknown IPs looks like spam
• Gradual increases with positive engagement build trust
• Warming approach:
• Week 1: Send to your most engaged subscribers only (opened/clicked recently)
• Week 2-3: Gradually expand to moderately engaged
• Week 4+: Continue expanding based on performance
• Volume increases might be: 1,000 → 5,000 → 15,000 → 50,000 → 100,000+ over several weeks
• Monitoring during warmup:
• Watch bounce rates (should stay low with engaged recipients)
• Monitor complaint rates (similarly low)
• Check inbox placement with seed testing
• Review ESP delivery metrics closely
• Slow down if metrics degrade
• Domain warming:
• If using new sending domains, they need similar gradual introduction
• New subdomains of established domains inherit some trust
• Brand new domains face extra scrutiny

Your ESP may provide warming schedules or automated warming tools. Follow their guidance while monitoring your specific results.