IP warming

a.k.a. warm up your IP
IP warming is the practice of sending low volumes of email on your dedicated IP and then systematically increasing your email volume over a period of time. This gradual process helps to establish a reputation with ISPs as a legitimate email sender. 
During the warming period, ISPs will evaluate your sending behavior and content to see how healthy your list is and how committed you are to deploying relevant information to responsive users. They even look at things like how many users opened your email, scrolled to the bottom, or moved your message to other folders.

As a general baseline, you should send at least 50,000 emails per month at least twice per month (for 100,000 emails total) in order to warm up your IP. This means that if your email volume is going to be really small but steady on a dedicated IP, you don’t need to worry about warming up. Most reputation systems only store data for 30 days, so you should not go 30 days or more without sending on an IP. If you do, then you will need to warm it up again.

In short, warming up an IP involves ramping up email volume over a specified period of time. Here's an example of how it's used: "Tell your client we're ready with the email campaign but the IP is still warming."
See also : address  ippie  e-mail or email  IP  ISP  
NetLingo Classification: Online Marketing