Warming your way to a good reputation

The Art of Warming

Whether you’re moving to a new Email Service Provider (ESP) or simply adding new IPs or domains to your current email program, ‘warming’ is one of the most important steps to establishing a good sender reputation with Internet Service Providers (ISPs) and maintaining strong email delivery performance.  Warming a new IP or domain is the process of gradually increasing volume from each over a certain amount of time, based on total volume you plan to send daily – usually following a customized schedule developed by your ESP.  The overall goal is to be considered a legitimate email sender by the ISPs, and to build a positive reputation.

Warming an IP or Domain

When you get a new IP or domain, it is known as ‘cold,’ meaning it has been dormant for some period of time, and no longer maintains a sender reputation.  When campaigns are sent from new IPs or domains, the ISPs evaluate them more carefully in an effort to protect users. If they didn’t take these precautions, the “true” spammers would be able to get away with a lot more.  During the evaluation process, ISPs pay close attention to volume, complaints, engagement, relevancy and list hygiene.  With volume being one of the main items monitored, it is best to begin sending low volumes with gradual increases toward the maximum daily volume.  This can take up to 60 days, and over this period, it’s also crucial to monitor other key performance indicators, such as bounce rates (<10%) and complaint rates (<.1%), while continuing to follow email best practices.

Along with gradually increasing volume over several days, it’s important to begin with your most engaged audiences on each list.  One common best practice is to identify recipients who have opened or clicked in different ranges of recency. From there you can send to your most engaged users first at the recommended volume and then increase as metrics reveal ISPs building a positive reputation of your campaigns. For example, if your max daily volume is 1M emails per day, a recommended warming plan might look like the below:


As you might notice, we recommend that you separate the Gmail recipients and follow a slower warming plan.  This is due to Gmail providing guidance around the way its system works.  For Gmail, sending at much lower volumes than other ISPs is ideal for long-term success.

Overall, warming new IPs and domains to establish a strong sender reputation with ISPs takes patience and time.  Start with your most engaged recipients first, then slowly increase send volume overtime.  Finally, remember that the end goal is to be considered a legitimate email sender and to build a positive reputation.