How to Warm Up an IP Address and Domain the Right Way 

This post is written by Will Boyd. Will Boyd is the Director of Deliverability Services at Simon Data. Over the last decade, Will has provided expertise to senders of all sizes and industries solving email deliverability problems. He has also optimized their sending practices for maximum inboxing.

In my experience as an email deliverability professional, there is no topic more misunderstood than the IP and domain warm up. If you’ve ever moved your email program to a new email service provider, you’ve likely felt some of the pain that needing to slowly introduce a new email infrastructure to the world of mailbox providers can cause. When done incorrectly or not done at all, warm up problems result in email messages being delayed or even rejected for delivery—additionally, an increase in filtering of delivered messages to the spam folder. However, a warmup process doesn’t have to be painful when done the right way with the right data. In fact, it is a wonderful opportunity to improve your sending reputation. Additionally, the process gets more email messages to recipients’ inboxes than ever before.


What is an IP Address and Domain Warm Up?


In short, domain warm up is a controlled and gradual way of introducing new sending infrastructure (IP address and/or sending domain) over time. This process allows the email sender to establish a positive sending reputation at the many different mailbox providers in the world. Once sending has begun, this process can span anywhere from two weeks to 30 days, which may seem like a while, but when done incorrectly, it can affect both delivery and the placement of messages in the inbox. Let’s take a closer look at why IP address and domain warm up is essential. 


Why is a Warm Up Necessary?


The email world is full of spammers and malicious messages. Therefore, it is critical to the overall survival of email that mailbox providers like Gmail, Yahoo, Hotmail, and all others, work hard to protect their users from spam. Even though it can feel like you receive a lot of spam in your inbox from time to time, these mailbox providers actually do a fantastic job of keeping the flood of malicious messages sent to you each day out of your inbox. 


The Problem with New IP Addresses and Domains

To continue doing such good work at protecting their users, mailbox providers rely on identifying both good and bad senders by their practices and by the infrastructures they use to send emails. In order to identify email senders and make better-informed filtering decisions, mailbox providers use IP addresses and domains to store data about that sender and their typical results. Whenever a provider of inboxes, such as Gmail, sees mail sent from a combination of IP addresses and domains they’ve never seen before, they don’t know if they are trusted messages or malicious spam. When they see a lot of these messages from an unknown combination of IP address and domain, they are very likely to treat those messages as spam until they feel comfortable that the messages are legitimate and wanted by recipients. This process of growing trust with the mailbox providers can take quite some time if messages are starting in the spam folder or are not delivered.


How to Get Started 

To quickly overcome the mailbox providers’ distrust, a strategic warm up process is critical when migrating to a new platform. A warm up process is simply a controlled, graduated introduction of a new sending infrastructure (IP address and/or sending domain) over time so the email sender can establish a positive sending reputation among the many different mailbox providers in the world. A sender utilizing a new combination of IP address and sending domain needs to begin their sending by delivering very few messages on day 1 of sending (50 messages is a good target for day one warming volume). Additionally, the sender should make sure to control the volume growth over subsequent days so that, at most, volume is never doubled from one send to the next until that sender has reached their typical volume of a day’s sending.


Below is an example of a warming schedule for a new sender utilizing two IP addresses:

warm up email domain example

What are the Steps to Email Domain Warm Up?


It is a common misconception that warm up processes are all about ramping up the volume at the right cadence. The truth is that volume ramp-up is only part of a successful warm up. While controlling volume is critical to success, the real key to a painless and effective email infrastructure warm up is to send email messages that produce signs, like opens and clicks, that indicate your messages are wanted by recipients. During these early days of sending on a new email infrastructure, mailbox providers look very closely at how their users are reacting (or not) to the messages from a sender they put into the inbox. Suppose a sender generates a lot of positive engagement from recipients and no spam complaints. In that case, subsequent days of volume increases will go smoothly and mail will continue reaching the inbox. However, the earlier and the more often those messages generate spam complaints, bounces to bad addresses, or even lack of engagement, the more hesitant that mailbox provider will be to accept and inbox messages at higher volumes from that sender. Thus, making sure a warm up process is strategic and not simply focused on volume is a huge key to email deliverability success.


5 Steps for a Successful Email Warm Up:


Step 1

Set up all sender authentication to align with the brand or organization doing the sending. While not necessary, mailbox providers like Gmail and Hotmail prefer to see the same domain used for authentication like DKIM and SPF as used in the from address.

Step 2

Set a target volume for a high volume day of sending over the next 35 days. 

Step 3

Ensure that the number of IP addresses used is appropriate for the message volume. Having too few or too many IP addresses can cause deliverability problems.

Step 4

Identify and order your subscriber list by their likelihood to engage positively with your messages. You do not want to send to addresses that are likely to register your messages as spam or to be bad addresses.

Step 5

Gradually begin sending via the new email infrastructure by starting with very small volumes on day 1 of sending and no more than doubling your volume each day that your sending increases. The suggested amount is to start with no more than 50-100 messages on day 1 of a warm up process.


How does Simon Mail Streamline the Domain Warm Up Process?


It’s this strategic focus that Simon Mail and Simon Data bring senders. Every sender that comes on board to our email sending platform, Simon Mail, not only receives expert assistance with technical setup, but also receives a custom warm up plan. This expert guidance based on each sender’s email strategy and typical volumes simplifies the warm up process and ensures success. As well, as a CDP with an email sending platform, we can help senders make decisions based on deep insight into email delivery data and any number of first-party data signals to provide the most accurate targeting of recipients possible. This results not only in warm up processes that are relatively quick and painless, but that end up improving the overall reputation of the sender getting them more email messages to the inbox than ever before.


Get More from your Warm Up (and your Email Program) with Simon Mail


The world of email is becoming more and more focused on recipient privacy. Simultaneously email spam filtering continues to rely heavily on recipient engagement with a sender’s messages to determine inboxing. Strategically utilizing email data alongside other first-party data points (like conversions, LTV, site visits, etc.) to make more informed sending decisions is quickly becoming the key to email deliverability success. A proper CDP fully integrated with an email sending platform, like Simon Data and Simon Mail, gives senders all the tools and expertise they need to start a new sending infrastructure off on the right foot and continue to deliver mail to recipients’ inboxes over time. 

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