IP Warming – Why is it Important and Best Practices

IP Warming is referred to as the practice of setting up the credibility and reputation of a new IP address by sending regular but small number of emails over a period of time and gradually increasing the volume. This gives Internet Service Providers (ISPs) the opportunity to evaluate and recognize your sending practices before giving the green light to your entire email list.

Why IP warming needed for a new IP address

ISPs look at every new IP address with suspicion as email spammers frequently change their IP address - once their existing IP starts getting blacklisted and identified as spam, they get a new IP. Due to this reason when email providers see emails coming from an IP with no history, they get concerned and carefully observe for unusual or high-volume activity. 

Email clients like Gmail, Hotmail, Yahoo check the email sent history for the previous 30 days of the IP address to deliver the emails to the inbox. So, it is important to build a send history of 30 days by starting slowly and sending to the most engaged customers first.

Why you may need a dedicated email IP

You may want to get a new IP address if you are currently using a shared IP and currently having deliverability issues. If there is a sender with poor email list, engagement or questionable practices on a shared IP, it will negatively impact everyone using the service on the shared pool.

For a dedicated IP address, you will need to be sending at least 100 thousand emails every month. However if you are sending more than 1 million email messages per day, you should consider getting a second dedicated IP address. Having 2 or more IP addresses for a company that sends over a million messages is a good practice so that even if one IP address performs poorly or gets a bad name due to some reason, you have another IP address ready that you can use for time sensitive campaigns and will not have to wait for warming a new IP.

How long does it takes to warm a new IP address

The IP warming process may take 4 to 8 weeks depending on the size of the sender's email list, list quality, subscriber engagement, send frequency etc.

IP Warming Plan

There are two steps to creating an IP warm-up plan - On the basis of campaigns and on the basis of subscribers.

1. On the basis of campaigns: Select campaigns that are non time-sensitive and can be throttled over several days without impacting business critical messages. You can also select campaigns that can be easily split between a new Marketing Cloud IP address and your existing IP address. Another plan can be to migrate smaller-volume triggered campaigns to Marketing Cloud before larger marketing programs.
2. On the basis of subscribers: This is done on the basis of sending domains (Gmail, Yahoo, Hotmail etc.) Identify the top 10 domains for your company. Focus on sending to your most active and engaged subscribers first since it can be the initial basis for the ISPs to determine your sender reputation.

Here is a general guide for North American ISPs. You can follow this IP warming plan for any domains where you have more than 20,000 subscribers. Follow the process until you’ve reached your complete audience by domain. 

ISPs & DOMAINS	DAY 1–3	DAY 4–5	DAY 6–7	DAY 8–14	DAY 15–21	DAY 22–28	DAY 29+
Gmail	5,000	10,000	20,000	40,000	80,000	160,000	320,000
All Others (AOL, Yahoo, and so on)	20,000	20,000	20,000	40,000	80,000	160,000	320,000

If you’re unable to collect or segment subscribers by domain, use the daily max IP address warming calendar. This method is slower but there’s no need for segmenting by domain. When you limit sending volume per IP address in this way, you fall within per-domain guidelines.

DAY	DAILY MAX VOLUME
1-7	50,000
8-14	100,000
15-21	200,000
22-28	400,000
29-35	800,000
36+	1,600,000

IP Warming Best Practices

• Send to your most engaged subscribers first. This can be done by looking at past emails and identifying subscribers who regularly open your emails and have good engagement like clicks, scroll downs etc. 
• Only send to contacts who have given implicit permission
• Use the content that has worked best for you in the past. Sending relevant content helps improve engagement.
• Ensure your emails are compliant with CAN-SPAM, GDPR, and CCPA by adding unsubscribe links, preference centre, email footer, and avoid spam words, etc.
• Regularly monitor your email metrics; if you notice any spam complaints or bounces, stop the process immediately and take action.
• Ensure your authentication records such as SPF/SenderID and DKIM/DomainKeys are correctly configured and validated.

Example Scenario

You are a leading sports apparel ecommerce company which uses Salesforce Marketing Cloud for email marketing and has a database size of 8m subscribers. You send over 4 million email messages each day and have only one IP address that is used for all your marketing email communications. One day while looking at your email send  performance report you notice that one of the ISPs is holding your emails and not delivering to the recipient inboxes. You discussed this with your SFMC consultant and he advises you to stop sending emails to the concerned domain for 3 months and try to figure out the cause. During these discussions, you also realize that you will need more IP addresses as you currently have only one and if it gets impacted due to any unforeseen circumstances, you will not be able to send any emails. At this time you decide to purchase four new IP addresses. Here are the steps you will follow:

1. Speak with your Salesforce Account Manager for purchasing new ip addresses
2. Look at you entire email list and identify the different email domains that you have and their numbers 
3. Identify your most active and engaged subscribers and inactive subscribers
4. Create the plan how you are going to send emails (starting numbers) to the different domains and doubling the volume every week until you complete the IP warming with your entire list
5. Create four new Delivery profiles with four new IP addresses
6. Create Five new Data Extensions - One for each new IP and one for your existing IP address
7. Create an automation that will populate the data extensions for four new IPs’ daily with an appropriate number of engaged subscribers representing different domains. Make sure you follow the suggested numbers and do not exceed. After populating the four DE’s for new IP addresses, the automation should populate the DE for existing IP addresses with remaining subscribers. The automation should shuffle the subscribers each day from one DE to another so that the new IP addresses get a chance to send email to different lists of engaged subscribers each day. This automation should double down the number of subscribers for each new DE every week and send the remaining subscribers to the DE for existing IP addresses.
8. As the automation updates the DE’s each day, send a suitable sender profile to send to different DE’s
9. Follow the process until you reach your entire list and complete the process of IP Warming