I think I just figured out how to do this... It’s pretty simple, really. Would love a MODx genius to take a look at it to see if there is a better way or check for security issues.
In the snippet code for Easy Newsletter, I inserted the following code between line 39 and 40:
LINE 39. if ($num < 1) {
//EMAIL CODE BEGIN
require_once('manager/includes/controls/class.phpmailer.php');
$mail = new PHPMailer();
$mail->IsSMTP();
$mail->IsHTML(false);
$mail->From = $from;
$mail->FromName = $from_name;
$mail->Subject = $subject;
$mail->Body = $message;
$mail->AddAddress($to);
$mail->send();
//EMAIL CODE END
LINE 40 $sql = "INSERT INTO...
In my situation, I have to use SMTP mail, which I configured in /manager/includes/controls/class.phpmailer.php.
It works though. Give it a try.