Getting rid of the annoying [Norton AntiSpam] tag

I'm running Norton Security Suite from Comcast.

 

It is taking incoming mail and changing the Subject line from, for instance,

 

Subject: Contact Info from Web site  ... and changing it to

 

Subject: [Norton AntiSpam] Contact Info from Web site

 

How can I get rid of that operation?  It's worthless to me, but a great annoyance as I FILTER messages based on the subject line.