Deliverability

IP Warmup

Definition

IP warmup is the practice of gradually increasing email volume from a new or dormant sending IP over several weeks, so mailbox providers can build a positive IP reputation for it. A fresh IP has no history; sending high volume from cold looks like spam and gets throttled or blocked. Warmup sends a believable, slowly rising curve to engaged recipients instead.

  • Needed for a new dedicated IP, or one idle for weeks; shared IPs stay warm in the pool
  • Ramp volume gradually, commonly over 4 to 8 weeks, never a cold full-list blast
  • Mail your most engaged recipients first so early signals are strongly positive
  • A conservative rule is to grow daily volume by no more than about 50% per day
At a glance
Applies to New or dormant dedicated IPs
Typical length 4 to 8 weeks
Daily growth Roughly +50% max (conservative)
Send to Most-engaged recipients first
Shared IP? No warmup; the pool stays warm
Pairs with Domain warmup

Why a new IP needs warming

Mailbox providers judge a sending IP partly by its track record. A brand-new dedicated IP has none, so receivers treat it with caution: spammers routinely buy fresh IPs and blast them, then move on. If your first act on a cold IP is to send tens of thousands of messages, you look exactly like that, and Gmail, Yahoo, or Outlook respond with throttling, spam-foldering, or an outright block.

Warmup avoids the trap by building a history deliberately. You start with a small daily volume to your most engaged recipients, then increase it on a steady curve. Each clean day (low complaints, low bounces, real opens) teaches the providers that this IP belongs to a legitimate sender, raising the volume they will accept. The same idea applies to an IP that has sat idle for weeks: its reputation has decayed and needs re-warming.

A sample warmup schedule

There is no single official schedule (your ESP usually supplies one tuned to your volume), but the shape is always the same: start small, roughly double every few days, and never grow daily volume by more than about 50% at a time. A common conservative ramp toward a meaningful daily volume looks like this:

An illustrative IP warmup ramp (tune the targets to your real list size and ESP guidance) 
Day 1     50
Day 2     100
Day 3     500
Day 4     1,000
Week 2    5,000 per day
Week 3    20,000 per day
Week 4    50,000 per day
Week 5+   scale toward full volume

Rules that make warmup work

  • Lead with engagement. Send to your openers and clickers first. Strong early engagement is the single best reputation signal a new IP can earn.
  • Send daily and consistently. A steady cadence helps providers classify you as a good sender faster than sporadic bursts.
  • Watch the response, not just the calendar. If complaints rise or a provider starts throttling, pause the ramp and hold volume until the signals clear. Warm up per provider, since each reacts differently.
  • Authenticate from day one. Aligned SPF, DKIM, and a DMARC record must be in place before the first send.
  • Warm the domain too. A new IP usually means a new sending setup, so run domain warmup in parallel.

The IP warmup ramp

Provision a new dedicated IP with SPF, DKIM & DMARC ready
Send a small daily volume to your most engaged recipients
Increase volume gradually, by no more than about 50% a day
Signals clean: keep ramping Complaints or throttling: hold
Repeat the daily clean-then-grow loop for several weeks
IP has reputation; scale to full sending volume

IP warmup vs domain warmup

IP warmup Domain warmup
Builds reputation for A specific sending IP Your sending domain
Needed when New or dormant dedicated IP New or low-history domain
Typical length 4 to 8 weeks 2 to 4 weeks
Skip it if You are on a shared IP Rarely; the domain is always yours
Reputation travels? No, stays with the IP Yes, follows the brand

By the numbers

4 to 8 wk
The usual span to fully warm a new dedicated IP, depending on target volume and provider response.
+50%
A common conservative cap on how much to grow daily volume from one day to the next.
5,000/day
The bulk-sender threshold at Gmail and Yahoo; warmup matters most as you approach and exceed it.

Common mistakes

Sending full volume on day one
A cold IP with no history that suddenly sends at scale looks like a spam cannon. Providers throttle or blacklist it before you build any trust.
Ignoring provider signals during the ramp
Warmup is reactive, not a fixed calendar. If complaints climb or one provider starts throttling, hold volume until it clears rather than pushing the next step.
Warming with your worst recipients
Leading the ramp with unengaged or stale addresses produces weak opens and high complaints exactly when first impressions count most. Start with your best segment.
Warming the IP but not the domain
A new IP often pairs with a new sending domain or setup. Skipping domain warmup leaves the more portable reputation cold and limits the gains.

Frequently asked questions

How long does IP warmup take?
For a new dedicated IP, typically 4 to 8 weeks, depending on your target volume and how each mailbox provider responds. Lower-volume senders may finish sooner; very high-volume senders ramping toward hundreds of thousands a day take longer. It is driven by provider signals, not a fixed deadline.
Do I need to warm up a shared IP?
No. A shared IP is kept warm by the combined, ongoing volume of every sender in the pool, so it already has an established reputation. Warmup is only needed for a new or long-dormant dedicated IP. You should still warm your sending domain.
What happens if I skip IP warmup?
A cold IP sending high volume is likely to be throttled, sent to spam, or blacklisted, because it looks like a fresh spammer IP. The reputation damage can take weeks of careful sending to repair, so skipping warmup usually costs more time than it saves.
Should I warm up the IP and domain at the same time?
Usually yes. A new IP normally accompanies a new sending domain or setup, and the two reputations are built by the same gradual, engaged sending, so running IP and domain warmup in parallel is standard practice.
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026 ← Back to glossary