The response from the SMTP Server is just what it says. The email address does not exist on the server. When you add the CC Me, the message is telling you that it could not send to one of the email addresses, presumably the one in the first test.
1000's of these module have been sold, and everytime this issue comes up it is a problem with the email settings or the email address.
Check everything 5 times over. Copy and paste the sending email address into Outlook Express or whatever you use to send email and send it there.