by Sophie Daniline 
IP warming is the practice of gradually increasing the volume of emails that you send with a dedicated IP address. This gradual process helps to establish a reputation with ISPs (Internet Service Providers) as a legitimate email sender. Doing this helps you to establish a good sender reputation, and helps you successfully get your emails into inboxes.
Why do you need to establish a reputation with ISPs?
ISPs treat email send volume as a key factor when detecting spam. This means if you suddenly start sending from a new or ‘cold’ IP address, the ISP will pay attention. Establishing a good sender reputation through IP warming can really help with email deliverability. There are, of course, other factors involved (e.g. email authentication, and sticking to email sending best practice, however establishing a reputation with ISPs is still important.
Why do ISP’s look at new or ‘cold’ IP addresses?
It’s all down to those pesky spammers. Spammers often obtain new IP addresses and then send out as many emails as possible. They’ll continue like this until they damage their reputation and get blocked. Once blocked, spammers repeat the cycle…this time with a new IP address. Therefore, ISPs limit the amount of emails they will accept from IP addresses with no sender reputation.
What time frame are we looking at?
With IP warming, the goal is to build up approximately 30 days of desirable sending history. Your warm up schedule will vary depending on a number of factors including: list age, spam reports, domain reputation, list hygiene, user engagement, and content.
How do you start?
Before you start, you will need to prepare your subscriber lists. Here’s a few things that should be in place before you click send on any emails:
- Make sure you have put authentication records in place (SPF and DKIM). If these are not in place, it can significantly damage your IP warming efforts.
- Segment your data. You are going to want to use your most active and engaged subscribers, as this is one of the factors that can influence your reputation.
- Create your content. Ensure you are sending emails that strengthen your relationship with subscribers. The more engaging and interactive the content, the better. You want to be showing ISPs that your content is content your subscribers want.
- Keep your delivery metrics in mind. The key metrics to watch out for are spam complaints and bounce rates.
How do you know if it is working?
During your first week of IP warming, make sure you are showing a consistent volume of sends, and keep this number relatively low. Pardot have a recommended IP warming plan but, if you don’t have that level of data to work with, you can start really small as long as you are consistently emailing each day.
Only increase the volume of sends if you didn’t see any deliverability issues in the first week. You’ll know it’s working if you’re keeping an eye on your delivery metrics discussed above. At this point, you can double the volume of your sends, but keep your subscriber selection in mind. It’s better to increase slowly with more active subscribers than try and rush with less active ones.
If there are still no issues, you can then start doubling or increasing your sending volume every few days until you reach your maximum.
If you see deliverability issues at any point, identify the problem and adjust your strategy. For example, by reducing your sending volumes again, or by pausing for a few days. If you can see a few mailboxes that are being affected, stop sending to those providers where the issues are happening. Once you’ve found the problem and can start sending again, build up slowly.
The really key thing to remember here is do not rush. Getting this right is important and you’ll set yourself up in good stead for the future if you do it properly.
Want help?
The IP warming process can be daunting, and if you’re doing it for the first time it can be helpful to have someone around to help. If you want help, please get in touch here.