Real Case solving a deliverability problem

At Digital Response, we often find ourselves facing particular challenges we must overcome. Today we will explain a recent case of one of our clients whose problem was the constant decrease in their campaigns’ Open Rate.

Situation overview

The client had apparent issues with their Open Rate. We decided to analyze the most important metrics (Open Rate, Click Rate, Hard Bounce Rate, Soft Bounce Rate, Unsubscribe Rate…) by domains, and we found out that the problem’s focus was Hotmail domains (,,,,,, More specifically, as you can see in the image below, Hotmail’s Open Rate was between 2% and 4%

At this point, we tried to fix the issue by keeping a close eye on the newsletter’s deliverability best practices: Text to HTML Ratio, newsletter deliverability control with tools such as Glock Apps; but we ended up concluding that it was going to be necessary to do a Warm-Up of the IP used to send to Hotmail domains. 

Warm-Up is the process of warming up the IP used to send the emails. The goal is to achieve a high reputation for the IP. 

How was the Warm-Up process executed?

The Warm-Up process was solely focused on the users with a Hotmail domain. The client classified this group into two types of users: ACTIVE, those who were sent emails regularly, and SEMIACTIVE, those who received communications less frequently.

Initially, we opted for a Warm-Up exclusive to Hotmail’s ACTIVE users, which were taken apart from the rest into a separate group that amounted to 250k users. These were then further divided into different, more or less homogenous groups to be gradually added to the deployments. 

On the first day, we sent emails to an initial group of 7k, formed by the most reactive users: had clicked twice in at least one campaign during the last seven days. Deployment after deployment, we slowly added the other groups, doubling each time the volume of users: 7k to 14k, 14k to 28k, 28k to 56k… and so on and so forth until reaching the 250k from the initial group of ACTIVE Hotmail users

During the process, we saw how deployment after deployment, Hotmail allowed the client’s campaigns to reach the users with that domain. In other words, the emails were delivered to the desired destination: the subscribers’ inbox. Thanks to the improvement in deliverability, the Open Rate considerably increased. In fact, the client now has an Open Rate between 14% and 21% for Hotmail

What’s the next step?

Like we previously said, the Warm-Up process for users with a Hotmail domain started up with the group of subscribers considered ACTIVE. Now that this segment’s process has concluded, the same procedure will be carried out with the SEMIACTIVE group. Up to this point, this group had been excluded from the campaigns since the Warm-up has to be a gradual process, and priority must be given to those users with more engagement. 

Besides that, we will continuously monitor and control the metrics to ensure that Hotmail’s deliverability stays stable, positively affecting the Open Rate of the users with this domain. 

We will keep you updated on this new phase!