From the "How It Works" section on the developer's web site: " Our server then compiles the alert e-mail and sends it to the e-mail address you have specified during setup. Because the alert e-mail is sent by our server, and not by the stolen mac itself, it does not rely upon SMTP and the delivery is guaranteed." See? It does NOT rely on the an SMTP server itself, it contacts another (via http I presume) and that server sends the e-mail. I'm seriously considering purchasing this software, but I always forget to change my Location setting, so I'm afraid it will report me to myself many times.