What Is Email Warm-Up? A Complete IP Warming Guide

If you have ever launched a new email marketing program or switched to a new sending domain and seen your emails land in spam, a missing or rushed warm-up is likely the cause.

This guide explains exactly what email warm-up is, why it matters, and how to execute it correctly.

What Is Email Warm-Up?

Email warm-up is the process of gradually increasing the volume of emails sent from a new IP address or domain over several weeks. The goal is to build a positive sending reputation with Internet Service Providers (ISPs) like Gmail, Outlook, and Yahoo before sending at full scale.

ISPs monitor new sending sources closely. A brand-new IP that suddenly sends 100,000 emails in a day is a classic spammer pattern. By starting small and increasing volume predictably, you prove to ISPs that you are a legitimate sender.

Why Is Warm-Up Necessary?

Every IP address has a sender reputation — a score based on:

• Volume and consistency of sending
• Bounce rates
• Spam complaint rates
• Engagement rates (opens, clicks, replies)
• Blacklist status

A new IP has zero reputation history. ISPs cannot distinguish it from a spammer's freshly provisioned IP. Warm-up gives your IP time to accumulate positive engagement signals.

Without warm-up, even a legitimate sender with a clean list can see:

• 30–60% of emails landing in spam
• Temporary blocks from Gmail, Outlook, or Yahoo
• Permanent IP blacklisting in severe cases

IP Warm-Up Schedule

Here is a standard warm-up schedule for a new IP:

Week	Daily Volume
Week 1	50–200
Week 2	500–1,000
Week 3	2,000–5,000
Week 4	10,000–20,000
Week 5	40,000–50,000
Week 6	100,000+

For high-volume programs (1M+ emails/month), extend the warm-up to 8–10 weeks.

Domain Warm-Up

A new sending domain also needs to be warmed up, even if you are using a shared IP pool. Domain reputation is increasingly important — Gmail and Outlook both score domains independently of IP reputation.

For domain warm-up:

1. Start sending small volumes from the new domain
2. Use the domain only for legitimate opt-in email
3. Set up SPF, DKIM, and DMARC before the first send
4. Monitor Google Postmaster Tools for domain reputation signals

What to Send During Warm-Up

Send to your best subscribers first. During warm-up, every open, click, and reply matters. High engagement builds reputation fast.

Prioritize:

• Recent opt-ins (subscribed within 30 days)
• Loyal customers who frequently open
• Transactional email recipients (they expect your email)

Avoid during warm-up:

• Inactive subscribers (no opens in 90+ days)
• Purchased or scraped lists (never, but especially not during warm-up)
• Large promotional blasts

Warm-Up for Shared vs. Dedicated IPs

Shared IP pool: Your reputation is influenced by all senders on the pool. Reputable platforms manage pool reputation on your behalf, but your sending behavior still matters.

Dedicated IP: You own the entire reputation. Full control, full responsibility. Required for senders above ~100,000 emails/month who need predictable deliverability.

MisarMail offers both shared and dedicated IP options with built-in warm-up scheduling.

Signs Your Warm-Up Is Going Well

• Spam rate below 0.1% (check Google Postmaster Tools)
• Bounce rate below 2%
• Inbox placement above 90%
• No blacklist listings
• Open rates consistent with your historical benchmarks

Signs Your Warm-Up Is Struggling

• Spam folder placement above 10%
• Soft bounce rate spiking
• Complaints above 0.3%
• Gmail or Outlook deferrals in bounce logs

If warm-up is struggling, reduce volume immediately and re-engage your cleanest subscribers before trying to scale again.

See also: How to Improve Email Deliverability

Start your warm-up with MisarMail's built-in scheduling →