Obtención de resultados inesperados al procesar correo electrónico a través de la aplicación App Engine

I'm trying to set up the email receiver found aquí, to process incoming emails and send them out as POST data to a script on my server to be handled further from there. The issue I'm having is when I send one test email to foo@[myappname].appspotmail.com, the App Engine logs show that the email is continually "received" over and over again every couple of minutes, even though I only sent it once. Then after several minutes of this, when I go into settings and disable the app, I get at least one "Delivery to the following recipient failed permanently" message to the email account I was sending the emails from (makes sense, since the app is now disabled and not accepting any incoming mail).

What I'm having trouble understanding is why the application is behaving like it's getting multiple emails sent to it when it's only one. Do I need to modify the Python script to do something to delete or halt the email once it's been processed the first time? If so, does anyone have any suggestions as to how to do that? The Python script that I'm using is found aquí.