What is IP warming and why is it important?
ISPs like Hotmail and Gmail use the IP address that you send from as one of the key factors to determine whether to deliver your mail to recipients inboxes, their junk, or even reject it completely.
If you suddenly start sending large volumes of traffic from a brand new IP, ISPs won’t have any record of you as a sender, and will likely view this as suspicious behaviour. As a consequence, you’ll usually start seeing a lot of your mail being rejected.
IP warming therefore is the process of gradually increasing the amount of mail sent from a new IP address to give ISPs time to get used to you as a sender, and slowly build up your sender reputation.
It’s far simpler to build up a positive IP reputation as a new sender than it is to repair a damaged IP reputation later on, so it pays to be as cautious as possible while warming a new IP.
Ensure your IP warming is a success
ISPs such as Gmail and Hotmail are looking for consistency from senders. Any sudden spikes of volume or large gaps between sends can impact your sender reputation.
Target your active and engaged users right from the start. Response rates, along with sending consistency, are key to your new IPs reputation. By targeting your most engaged recipients right from the beginning, it should mean your IP gets the best possible reputation boost.
Make sure you’re checking the bounce and blocked rates after each send- if these are over 3% on any campaign, we’d suggest not increasing the volume on the next send as any further increases in volume or negative results could quickly lead to your IPs reputation being tarnished irrecoverably.
What if my results start to decline?
If your results do drop at any stage, refrain from sending for a few days and then send to a smaller set of data, preferably one that you’ve already established as more engaged. This should give you the best chance of re-establishing ISP’s trust with your sends.
During the IP warm up period, results up period can vary significantly by ISP. For example, if Hotmail is showing much lower results than other inboxes, create a segment and exclude the Hotmail addresses. You can then ramp these up in a much more gradual and controlled way to ensure your reputation is protected.
What should I do once I’ve finished warming up my IP?
Once you’ve finished, you’ll want to ensure that your sender reputation remains as strong as possible. One of the best ways of doing this is to segment your recipients and tailor your messaging in line with engagement levels. Read our guide on segmenting by engagement that explains a bit more about how we recommend doing this.
If you’re interested in finding out more about email deliverability, please have a look at our comprehensive deliverability guide.