Blog post

Static vs Dynamic: How to Personalize your Emails

E-mail personalization can bring substantial added value to your business, as it directly increases your online traffic when done correctly. Our experience from working with our customers shows uplifts of up to 30% CTR increase when comparing personalized recommendations with popularity recommendations.

However, personalizing emails is not straightforward for a few reasons:

#1. Huge variety of ESP (Email Service Provider) tools & email tools to read the content clients available

#2. Emails have existed since the 1990’s and have barely evolved since then

In this blog post we will give an overview of the different scenarios that are available for sending personalized emails to your audience using Froomle as a recommendation provider.

Use cases

There are many different use cases for email personalization, such as daily emails, funnel-based mails (conversion, re-activation, …) or time dependent newsletters (weekly, monthly etc). Depending on the use case some integration options are more or less preferred.

Integration options

The first major architectural decision to make is whether to use recommendations generated at email creation time (static) or generate recommendations on the spot when the user opens the email (dynamic).

The static option is the easiest one, but has the downsides of:

> Having to compute recommendations for every single user regardless if they will ever open the mail (impacting system load & computation time)

> Not taking into account the most recent user interactions (users could have read an article by the time they open the mail and see the recommendation)

The dynamic option does not have these downsides, however it also comes with its own set of complexities dependent on the option you decide to implement. We will further explore different kinds of integration for both static and dynamic integrations.

Static- Pre-Computed Batch recommendations

You need to first configure/modify your ESP to request Froomle recommendations via our Batch recommendation process while preparing the mail campaign. This can be manual or automated. The results have to be integrated into the emails before sending out the campaign so that each user receives a personalized email.

Static- Pre-computed Recommendation API

You need to configure/modify your ESP to request Froomle recommendations via our regular recommendation API  while preparing the mail campaign. The results have to be integrated into the emails before sending out the campaign so that each user receives a personalized email. To avoid long delays and overloading the system, this process should not be used for targeting more than 10.000 users at the same time.

Dynamic - Accelerated Mobile Pages (AMP)

AMP for email allows senders to include AMP components inside rich engaging emails, making modern app functionality available within email. The AMP email format provides a subset of AMPHTML components for use in email messages, that allows recipients of AMP emails to interact dynamically with content directly in the message. AMP allows you to request recommendations from the Froomle API directly when users open the mail.

Unfortunately not all email clients support this technology, so you’ll need an html fallback for your e-mails.

Dynamic - Dynamic Email Recommendations using Image Replacement

 Most dynamic emails leverage dynamic images. The concept is relatively simple: 

> E-mails are sent containing a virtual image virtual_reco_for_john.jpg and link virtual_reco_for_john.html

> When the user opens the email and attempts to download the image, the server fetches live recommendations and replaces the image with actual_article_for_john.jpg

> When the user clicks the link, the server redirects the browser to actual_article_for_john.html

The benefit of using this approach is that it works with virtually every email client. The downside is that ALL information needed in the e-mail needs to be embedded within the image (actual_article_for_john.jpg). For example:

If you have in house technical expertise, Froomle offers the image redirection functionality in beta. It requires you to generate combined images, for which you can use an image creation tool (e.g. dynapictures, bannerbear, apitemplate, …). 

There are software companies specializing in the image replacement technique. Setting this up will be more flexible and require less effort from your side, however it requires paying for an additional license.


E-mail has quickly become a key channel for all industries, and holds plenty of opportunities to be an even stronger and converting channel.  For digital publishers specifically, newsletters are an important tactic for engagement of their subscribers and making them as relevant as possible helps to keep a subscriber loyal. Whether it be static pre-batched recommendations for all your users, or a dynamic individualized option that takes into account real time data, there are plenty of options for all levels of technical expertise to wow your reader. 

Curious to see how Froomle can help boost your email personalization? Let’s Chat!

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