Those undaunted by the challenge of antivirus filtering should be prepared to purchase, install, and maintain a veritable laundry list of products. Starting at the company firewall, you'll need to consider a product such as Norton AntiVirus 1.5 for Firewalls (Web site). The software scans the data flowing into and out of the firewall connection for viruses, and receives automatic virus-definition database updates from Symantec.

Next, if you're running a POP3/SMTP e-mail server, pick a package such as Norton AntiVirus 2.1 for Gateways, Trend Micro's InterScan for Internet Gateways (Web site), or Ositis Software's Win Proxy 3.1 (Web site). Each product essentially acts as an e-mail proxy server, with incoming mail flowing through it before reaching your in-box at the mail server. Conversely, all outgoing mail passes through the software before heading to the Internet from the actual mail server. As mail passes through Norton AntiVirus for Gate ways, for instance, it's scoured for tag-along nasties. If found, the infected attachments are deleted or quarantined, depending on how you've set up the software. The system can then automatically notify the receiver, sender, and administrators that a virus was found in the specific e-mail.

If you're using Lotus Notes or Microsoft Exchange, opt for a similar product-specific antivirus application such as Norton Anti Virus 2.0 or Trend Micro Scan Mail. Exchange administrators should also familiarize themselves with the new Exchange Virus Scan API (AVAPI) included with Micro soft Exchange 5.5 Service Pack 3 and Microsoft Exchange 2000.

Some products in this category, such as Symantec Mail-Gear, include built-in mail-content filtering. And Praetor 1.5 from Computer Mail Services (Web site) lets administrators also ban spam by creating lists of banned domain names and IP addresses.