IP Warming Best Practices: Warm it Up without Burning it Out

February 11, 2022
By AtData

How to Warm-Up an IP Addressshutterstock_1836307909

You can't run a marathon or sing an opera without warming up first. The same goes for sending email on a new IP address. Here are some IP warming best practices to get you moving in the right direction. 

Warming a new IP address instead of starting out sending at full volume lets you build up a good sender reputation with the ISPs.   At first you'll send only a comparative trickle of emails, but you can increase volume gradually if you detect no deliverability or engagement issues.

  • ESPs adopted the IP warm-up process to work with ISPs that rely on sender reputation to decide whether to send emails to the inbox, the spam folder or oblivion.
  • ISPs get suspicious when emails flood in on unknown IP addresses. So, ESPs find they can deliver better when they throttle back on email volume until senders can build up good reputations.

During the IP warm-up, the ISPs watch whether you manage email responsibly. Removing undeliverable and spam complaint addresses help you build a good reputation, but repeatedly emailing undeliverable accounts hurts it.

At the end of the IP warm-up period, you should be able to start emailing at a normal volume without risking your sender reputation.


5 tips to solve IP warm-up problems

How long that process can take, and how much you must reduce your sending volumes during the IP warm-up period, are two issues that can cause problems for emailers. Ramping up email too quickly in this crucial period could lead to delivery or inbox placement problems, especially at Gmail.

Even a 100% permission mailing list that has gone through best-practice hygiene can find messages disappearing into a spam-folder black hole if you ramp up too aggressively.

If you see falling open rates and inbox placement despite following all best practices during IP warm-up, these recommendations can help you pinpoint and fix the problems:


1. If you note a major problem on a specific day in the warm-up, check your ESP's reporting for problems on that day.

It's possible that it took longer than usual for the numbers to populate. See whether everything is correct now.


2. Look for problems in your deployment infrastructure.

Did someone accidentally change a setting that caused authentication to fail? That could prompt an ISP to reject messages.


3. Review whether the addresses you're sending to in later stages of your IP warm-up are still fresh and active.

You might have started out mailing to the best addresses on your list, but as you message deeper into your file, you could be tapping potentially problem addresses, producing lower engagement.

Some of those addresses might generate spam complaints and blocks, and those are two strikes against your sender reputation with the ISPs.


4. Check with your email verification service to learn how it cleaned your email addresses before deploying.

Most hygiene services simply ping the email addresses on your list to check whether they’re deliverable or not. This is only one small piece of the deliverability issue. Addresses we call "deliverable but problematic," including spam traps, honeypots, heavy spam complainers, disposable addresses, role accounts and the like, can grind your email marketing program to a halt.

  • Sometimes, hitting just one spam trap is enough to get blacklisted.
  • A comprehensive email hygiene service needs to flag deliverable but problematic address, correct inadvertent hygiene errors, validate the deliverability of all email addresses that survive the first two screens and guarantee the deliverability of these email addresses.


5. Cut back on your daily sending volumes.

You might be following your ESP's recommendations, but it's easy to run afoul of ISP tolerances. Gmail reps recommend starting as slowly as possible, for at least the first couple of days.


Also, try to target the most engaged users first.

If your IP warm-up schedule runs a week or less, you could be emailing too aggressively. The graphic below shows what could be used for a large sender when warming up a new IP address:



Need help with an IP warm-up?

Warming up your new IP addresses is essential when launching a new email-marketing program off the ground or when switching email servers or ESPs. Your deliverability and inbox placement depend on it.

Choose your addresses carefully, and take time to build volume to establish a good sender reputation. Your brand managers might chafe at the delay in moving to full volume, but you can't afford to take shortcuts. Negative results during this period will result in lower engagement and results in short order.

We're happy to answer questions and put our years of experience to work helping you negotiate this critical step in your email journey. Reach out anytime!



FreshAddress partner LuxSci recently published a blog post titled “Warming Up Your IP Addresses Automatically" that we are excited to share with our readers. This article serves as the perfect update and complement to our previous commentary on the topic. It even contains an updated IP warm-up schedule.

Read the article: Warming Up Your IP Addresses Automatically


Don’t Forget About Hygiene When Assessing Problems!

Are you following IP warm-up best practices but still seeing open rates and inbox placement dip? If so, we recommend that you take a long, hard look at your email hygiene practices, and your provider if you have one.


Why a Simple “Ping” Won’t Do:

Do you know how your list is cleaned before deployments? If your provider only performs a simple SMTP check or “ping”, this could be the reason for your problems.

Why? Because this doesn’t catch what FreshAddress calls “deliverable, but problematic” email addresses. These include bad addresses like:

  • Spamtraps;
  • Honeypots;
  • Heavy spam complainers;
  • Disposable addresses; and
  • Role accounts.

A simple “ping” won’t catch these addresses. Remember, hitting just one spamtrap can lead to blacklisting. There's no faster way to bring your email marketing program to a halt.


So, what can you do?

Use a comprehensive email validation service like SafeToSend® to keep you out of trouble. SafeToSend:

  • Flags toxic but deliverable addresses (spamtraps, honeypots, heavy spam complainers, disposable emails, role accounts)
  • Corrects email typos, syntax, and related errors
  • Confirms Valid, SafeToSend deliverability with 100% delivery promise

Want to learn more about SafeToSend email validation and hygiene? Contact us today.

Have questions about IP warm-up best practices? Speak with your ESP or request a consultation with LuxSci.