IP warming, or IP warm-up, is the way you establish a reputation for a new IP, or an IP that has not been used for some time. The warm-up process involves sending email from the new IP starting with small volumes, and gradually increasing the volume of email each day or week according to a set schedule. The goal is to develop your identity and gain the mailbox providers’ trust, and increase your chances of getting your email delivered to your subscribers’ inboxes.
Mailbox providers are suspicious of email coming from an IP that has no reputation or that has an unfamiliar sending pattern. They have to protect their customers from spam, so they will block or bulk large volumes of email from new IPs, because it is most often coming from spammers. That’s why you need to use best practices to warm up your IPs before your send your normal volumes from your new IP, to show the mailbox providers you are serious about having a good reputation.
Read the How to warm up an IP address article for all of the details you need to know.