How to warm up an IP address (and a new domain)
Providers throttle senders with no history. A realistic warm-up schedule, the signals that say slow down, and what resets the clock.
Deliverability · 3 min read · updated
Why cold senders get blocked
Mailbox providers rate senders on history, and a new IP or domain has none. From their side, a sudden burst of mail from an unknown source is exactly what a compromised server looks like — so they throttle first and observe later. Warm-up is the process of building the history deliberately, at a pace providers will accept.
This is not a formality you can skip by being legitimate. The providers cannot see your intentions; they can only see your volume curve.
A schedule that works
Exact numbers vary by list quality; the shape does not. The constant rule: send to your most engaged recipients first, because early positive signals — opens, replies, not-spam — compound exactly like early complaints do.
- Days 1–3. 50–200 messages per day, to people who opened or clicked in the last 30 days. Nothing else.
- The ramp. Roughly double every two to three days while the metrics stay clean. 500, 1,000, 2,500, 5,000 — resist the urge to jump.
- Per provider, not just in total. Gmail, Microsoft and Yahoo each rate you separately. Spread each day's volume across them rather than warming one at a time.
- The hold rule. Any spike in deferrals (4xx responses), bounces or complaints means hold at the current volume until it clears — or halve it. Pushing through a throttle is how a throttle becomes a block.
The domain warms separately from the IP
Reputation attaches to the DKIM-signing domain as well as the IP. A brand-new domain on a beautifully warmed shared pool still has no domain history, and still needs a ramp. This catches people who switch providers and assume the new provider's IPs carry them — the IPs do, the domain does not.
It also means a rebrand to a new domain is a deliverability event. Plan it like one: overlap the domains, ramp the new one, and do not burn the old one's history the day the logo changes.
What resets the clock
- Going quiet. Roughly a month of silence and the history starts to decay. Reputation is a moving average, not a trophy.
- Volume whiplash. 10x-ing your daily volume for a product launch reads exactly like a compromise. If a big send is coming, ramp toward it over a week.
- A new audience. Importing a large cold list mid-warm-up undoes the careful engagement profile you just built. Warm up on your best people; add the rest gradually after.
Common questions
How long does IP warm-up take?
To reach six-figure daily volumes, typically four to eight weeks. Small senders reach their cruising volume much sooner. The schedule is set by how providers respond, not by the calendar.
Can I skip warm-up on a shared IP pool?
The pool's IPs are already warm, so partly — but your domain still builds its own reputation from zero. A gentler, shorter ramp is still the right move.
What do deferrals during warm-up mean?
The provider is saying "not this fast". A 4xx is a temporary refusal, and the correct response is to hold or reduce volume and let the queue retry. It becomes a real problem only if you keep pushing.
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