Norton Corporate AV and third party email

Hello all,

I haven't posted in a while, but I have been reading when I have time.

The IT staff at the organization where I work put out a memo saying that no one can use third party email (Hotmail, AOL, MSN, etc.), on-line game sites (Pogo, EA Games, Yahoo Games, etc.), or on-line shopping sites any more because they open the network to virus attacks. The memo says these sites allow "holes" for attacks, and that a "system wide" virus attack recently occurred because of the use of third party email. The client machines are all Windows 2000, anti-virus is Norton Corporate, and the email is through MS Exchange.

I thought that if Norton Corporate was configured properly it would protect against virii (sp?) no matter how they tried to come in. I read that with Norton 2003, as long as auto-protect was on, it protected against any intrusion by a recognized virus and I assume Norton Corporate is similar. I understand that third party email will not come in through the company's email server, but I thought Norton would still watch for virus signatures.

I'm not really sure how on-line games work, but I assume some type of P2P connection is established (?), but shouldn't Norton still catch a virus that tried to get in?

Finally, I do not see how using on-line shopping sites "open gateways to the system that allow for the same types of attacks" (from the memo).

I searched on Google and here and didn't find complete answers to these questions. Am I really missing something here or is the memo not entirely accurate? :confused:

I'm trying to understand this, so if I'm just missing it I'd appreciate any feedback, but if my ideas are right I'd be happy for some reinforcement too.

Thanks.