It takes time to download the new fixes to each desktop.

It is expensive, it creates a bottleneck at the mail server, and it isn’t clear that such a scan will be all that effective.

Rarely will you need to get updates that often. The vendors are already very quick to get fixes out to everyone when a new virus appears. So daily updates will matter only if you are...

We are considering doing virus scanning on all incoming e-mail.

We aren’t just scanning for binary code inside an executable anymore. The bad code could be hidden in a password-protected Zip file or encrypted in SMIME [Secure MIME]. These are things we can’t even scan.