Norton is failing to catch an email bug

Hello all,

I am using Norton 2011 currently after experiencing problems with 2012. Had to downgrade temporarily. --- On with the problem. ---The issue is a known email scam going around purporting to be a message about trouble delivering a package from the USPS. The email contains a zip file named "USPS report.zip" which contains a file posing as a PDF named USPS report.exe that, when executed, will download a file from a Russian server. Nuff said about that but the trouble is Norton will scan this file and report it as SAFE and this is NOT SO.  A friend at work attempted to "print the shipment label attached" as the email instructs and much trouble was caused. Now it's been a short time and the email arrives in my box. Knowing about it I decided to see why Norton Email scanning let it through without flagging it. Trouble is Norton won't flag it even with a manual/custom scan. In my eyes this is bad bad bad. If anyone can elevate this issue it needs to be looked into.