MS Proxy Server & Virus

I have a network of 30 users on Win 98SE and 2 NT servers one as a PDC and the second as a File server, I have installed MS Proxy Server 2.0 on the File server, and we donot have MS Exchange server. My question is, is it possible to filter out internet e-mails with an antivirus program or through a function of proxy server for viruses before the users get the email on their workstations. I would appreciate any comments.