Why It Matters
A new IP address has zero reputation — and zero reputation means zero trust. If you send 100,000 emails from a fresh IP on day one, every major ISP will throttle, defer, or outright block those messages. They've learned that sudden high volume from unknown IPs almost always means spam. Warming solves this by proving, gradually, that you're a legitimate sender who people actually want to hear from.
How It Works
You start by sending a small number of emails — typically 50 to 200 — to your most engaged subscribers. These are people who regularly open and click your messages, so they'll generate positive engagement signals. Every few days, you increase volume by 30–50%. Over 4–6 weeks, you ramp up to your full sending volume. Throughout the process, ISPs are watching: Are recipients opening? Clicking? Reporting spam? The answers shape your IP's reputation for months to come.
Quick Tips
- Send to your most engaged subscribers first — their opens and clicks during warmup set the foundation for your IP's reputation
- Monitor bounce rates and spam complaints daily during warmup; if either spikes, pause and investigate before continuing
- Don't warm an IP and a new domain simultaneously if you can avoid it — warm one at a time so you can isolate issues