Warm it up! The why and how of an IP warmup

What's an IP warmup? Why does it matter? These questions and more answered in this blog post.Often when we have new senders or senders who acquire a new dedicated IP address, we get questions about how to best warm up the IP addresses – or even why a warmup is necessary. A “cold” IP, or an IP that has sent little or no traffic in the preceding 30-45 days, will require a ramp-up period to ensure the best delivery to ISPs and mailbox providers. The ramp-up typically starts with a small number of emails per day per IP and volume doubles every few days. This allows the ISPs to see a gradual increase in traffic and establish a sender reputation for the IP(s).

Does an IP warmup really matter?

Certainly, it seems easier to just send all your normal traffic over your new IP. Ramping up a cold IP will most likely require some changes to your sending schedule and some manual oversight – but in most cases it’s a relatively minor inconvenience for a sizable reward. When a ramp process doesn’t take place, ISPs will often do one of three things:

#1: Rate limit the mailings. Only a small percentage of the mail will be delivered each hour, to prevent large quantities of unexpected mail from hitting subscribers at once. In many cases, once a certain threshold is met, the ISP will graduate from rate limiting to one of the next two options.

#2: Route mail to the spam folder. If too much volume is sent too quickly, many ISPs see this as a sign the mail server may be compromised, and they will be more likely to route messages to the spam folder instead of the inbox. The “big 4” ISPs are more likely to take this action as a first step, escalating if the volume persists and/or subscriber engagement metrics are negative.

#3: Block mail outright. While this option is less common than the others, there are mailbox providers that will reject mail sent in excess of their defined thresholds for a specific IP address.

How should you properly warm up your IP address?

There are many methodologies around warming up an IP address, but most are going to depend on the makeup of your list and your sending frequency. WhatCounts clients receive a custom ramp plan based on these factors and others, but in all cases there are a few items to keep in mind.

#1: Start small. If your IP address has been dormant for at least 30 days, it may be beneficial to start with as few as 1,000 emails per day. If you’ve been sending small amounts of traffic over an IP, (such as transactional emails), you will likely be able to start a little higher.

#2: Start with the most engaged. If you’re tracking user engagement, (you should be), find your most engaged subscribers and send to them first. These users are more likely to open, click, and otherwise positively interact with your messages, and less likely to lodge spam complaints.

#3: Stop if needed. During your ramp process, it’s possible you may run into delivery issues that require attention. If you see spam folder placement increasing instead of decreasing, or bulking turn into blocking, it may be necessary to slow down the ramp process. Usually, holding steady at the then-current volume while the issue is investigated is the best course of action. Once the issue is addressed, the ramp process can resume.

Smooth sailing ahead

If you follow these basic rules, it’s highly likely your IP warmup will go smoothly and establish a solid delivery foundation for your IP address going forward.

As always, if you have questions, please reach out to the WhatCounts Support team for assistance.

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