Using Sparkpost, I get a “Forbidden” error message when I try to validate the delivery server.
The error message can look like:
Cannot send the confirmation email using the data you provided. Here is a transcript of the error message: Forbidden.
This happens because when you have created the SparkPost api key, you haven’t checked all the permissions, so best is to generate another key, this time by checking all permissions, and use the new key.