Register new template

To register new emails, developers should use the following code:

public function register_emails( $yaymail_emails ) {
    $yaymail_emails->register( YourNewEmail::get_instance());
}

add_action( 'yaymail_register_emails', 'register_emails' );

This code attaches to the yaymail_register_emails action hook. It is used to register new email templates by passing the email instance.