Are you sure your contacts are interested in your emails? Data has the answer!


Even today, emails are one of the most used communication tools, enabling a brand to interact with existing and potential customers.

In this article, you will see how to measure your contacts’ engagement levels, to help you answer questions like “Who are the most active contacts on the email channel?”, “Who has lost interest?” and “Are there contacts that registered a little time ago, but are not active?”

About the algorithm

Emails are still an effective channel for sending push notifications to contacts, with the aim of engaging and interesting them.

The measurement of contact activity on the email channel is essential to a brand, especially when carrying out communications plans, or perhaps reviewing marketing strategies. With this goal in mind, Contactlab recommends the Email Engagement Index, which enables you answer questions such as those listed above and do much more.

You can, for example, identify the contacts that follow you most by email, who has dropped off, those who have recently subscribed to your newsletter but are not responding to it, as well as people who were extremely active in the past, but appear to have lost interest.

Email Engagement Index

The algorithm result is immediate and easy to understand. Every contact profile is enriched with a value that represents their engagement level, which is based on how they reacted each time they received an email from your brand. Values such as:

  • Engaged: Recently very active.
  • Active New: Recently registered, with activity.
  • Interested: Not very active recently.
  • Dormant: No recent activity.
  • Disengaged: Very active, but not recently.
  • Inactive New: Recently registered, with no activity.
  • Inactive: No activity.
  • Off: Have not been contacted recently.

How do you calculate the Email Engagement Index?

Contactlab recommends two versions of the Email Engagement Index. The dynamic index, which will be described in a separate article, and the static one that is covered here.

To use the algorithm, data about your email deliveries must be available, which needs to include your contacts’ reactions after they receive them.

The level of detail you should consider for every contact includes:

  • Total number of emails received, opened and clicked.
  • The time passed since:
    • The first email.
    • The last email.
    • The last time the recipient opened a mail or clicked a link.
  • The activity index, which summarizes the email activity level in relation to openings and clicks.

It is also important to define the meaning of ‘recently’… to choose the time frame in which an action, such as an opening or a click, can be regarded as recent.

Actual time frames are defined according to how each brand communicates through email. Companies in different markets have diverse communication needs. Perhaps it is meaningful to communicate news and offers weekly, while in the fashion sector, the need is generally seasonal.

Each threshold can be configured according to the brand’s needs, for example:

  • Recently contacted.
  • Recently registered.
  • Activity
  • Activity recency.

The metrics that are taken into account, together with the threshold definitions, result in an engagement level for every contact on the email channel.


Angela subscribed to your newsletter on the website nine months ago. Since then, she has received 12 emails, opened nine and clicked within just three of them. In addition, the last opening was three months ago, while the last email was sent seven days ago.

Email Engagement Index

According to the industry sector and your email communication plans, the following thresholds have been defined:

  • Recently contacted: In the last three months.
  • Recently registered: In the last two months.
  • Activity: 15%.
  • Activity recency: Last month.

Angela has been contacted recently, seven days ago, but her last action was a long time before that, three months ago. Her engagement level is Disengaged: She has been very active in the past, but recently, she’s been inactive on the email channel.

How can you use this information?

Thanks to the Email Engagement Index, you can measure the success of your email deliveries and understand the interest level regarding your brand. As a result, you can plan more sophisticated deliveries, segment your audience and differentiate your communications. You can create engagement journeys, define reactivation strategies for contacts who used to be active and so on.

Find out more about Data and all the available algorithms. For more details, contact our Customer Care.