Symantec Security Gateway vs. Custom Linux Box?

michaelr asks: "I run several email-based discussion lists. While only members of the lists are allowed to post, I've lately had problems with viruses as they often impersonate the members (or the members themselves are infected). I've identified two solutions: either build a Linux box running SMTP-based antivirus software, or purchase something like the Symantec Gateway Security which includes AV among lots of other things. The street price makes it a little more expensive that a Linux box + AV software, but it seems to be zero maintenance. The problem: the Symantec device is new, and before I place my trust in it, I'd like to know: has anyone had any experience with it, or should I just build the equivalent myself?"