Python script to reject invalid senders

I wrote a Python script to reject e-mails where the sending address is invalid, and will work in Visnetic Mail Server (and should in Merak as well). The Python script gets called using a Content Filter, and connects to the mail server(s) responsible for the "MAIL FROM:" address specified. Once a successful connection has been made (lowest priority MX is tried first), and the e-mail address is verified to be valid or invalid, an action can be made using the Content Filter based on the exit code of the script. Directions on how to use the script can be found within the top of the script, and configuration options can be modified directly after the documentation. No additional Python modules are required, although the script will need to be able to execute "nslookup.exe", and Python 2.5 is recommended due to the "operator" module's shortcoming in previous versions.

The script can be downloaded from the following URL:
http://www.exoxe.com/code/validateemail.pys (rename it to .py if you wish after fetching)

Disclaimer: I am not responsible for any rejected/deleted mail if you wish to use my script. Remember to use the CF bypass file for problematic senders (you'd be surprised of the handful of people that send from non-existant e-mail addresses!) You may wish to run this in passive mode, meaning you do not specify the Accept/Reject/Delete action until you've looked over your logs and can determine it's working properly.

If you have any recommendations, please feel free to bug me - dustinPYTHONtravis@gmail.com (remove PYTHON)