IP warming: a 30-day schedule that actually works

A new IP has no reputation. Send 50,000 messages from it on day one and major receivers will throttle, filter, or outright block — not because the mail is bad, but because the silence before it was suspicious. Warming is the discipline of teaching receivers that your traffic is wanted, one careful day at a time.

The 30-day schedule

What you send matters as much as how much

• Day 1–7: send to your most engaged recipients only. Past 30-day openers are gold.
• Day 8–14: expand to 90-day engagers. Watch for any complaint uptick.
• Day 15–21: include 180-day engagers. Now you're testing list edge cases.
• Day 22+: full list segments. By now, reputation should be established.

Per-receiver warming

Gmail, Microsoft, Yahoo, and Apple maintain independent reputation models. A great Gmail reputation tells you nothing about your Microsoft standing. Most ESPs let you split traffic by receiver during warming so you can ramp each at its own pace.

The three signs you're moving too fast

1. Open rate dropping >20% day-over-day. Your mail is starting to land in spam.
2. Complaint rate above 0.3%. Receivers are now actively penalizing your IP.
3. Soft bounces above 5% with 4.7.x codes. The receiver is throttling — slow down immediately.

When to add a second IP

Most senders should run a single IP until they hit roughly 500,000 messages/month. Multiple IPs split your reputation and force you to warm each one — usually pointless until you have enough volume to differentiate traffic types (e.g., dedicated transactional vs marketing IPs).

Warming a domain vs an IP

Modern receivers weight domain reputation heavily — sometimes more than IP reputation. If you're moving to a new IP but keeping your sending domain, the IP warm is faster (your domain reputation carries some trust). New domain and new IP is the slowest path; budget 6–8 weeks.