Mail API
Our goal for this section is to see how we can send emails programmatically in Drupal 9. In achieving this goal, we will explore the default mail system that comes with the core installation (which uses PHP mail), and also create our own system that can theoretically use an external API to send mails. We won't go all the way with the latter because it's beyond the scope of this book. We will stop after covering what needs to be done from a Drupal point of view.
In the next and final section, we will look at tokens so that we can make our mailings a bit more dynamic.
The theory behind the Mail API
Like before, let's first cover this API from a theoretical point of view. It's important to understand the architecture before diving into examples.
Sending emails programmatically in Drupal is a two-part job. The first thing we need to do is define something of a template for the email in our module. This is not a template in the traditional sense...
