Hello @Marcamilleri,

When you mean you’re looking to add a customer review widget to an email are you talking about a method for your recipients to give a review or are you looking to display a customer testimonial in an email?

If you’re looking to collect reviews from your contacts directly in an email, the best way would be through the use of the update profile property function we offer that’s described in our Include Ratings Links or NPS Surveys in an Email Help Center article. Our template specialist, @Anna McCarthy also has a great walkthrough video in the Community post below that she shared recently:

Typically using this option would be the best option as often times, inbox providers will strip out any additional codes or embedded content as they may seem suspicious. I’ve explained this in more detail previously in the Community posts I’ve shared below:

You may also find some luck using third-party softwares such as TypeForm which offers a great alternative to embedding a review survey in an email. 

If your goal was to dynamically display a customer testimonial in an email, you can typically do so through the use of a custom web feed. You can find my answer to a similar question in the following Community post which elaborates on this feature: 

I hope this helps!

David