For the average home-user, anti-virus software is a must. A personal firewall such as Zone Alarm and running a program like HFNetcheck, which is a free download for personal users. It checks your system to see if anything needs to be patched. I'd also recommend a program such as SpyCop to periodically check for any spyware on your system.
As every new breed of virus is conceived, created and released into the wild, another small change is made to the anti-virus software to combat the new threat.
For the average home-user, anti-virus software is a must.
I want to avoid locking people into solutions that work only with Postfix. People should have a choice in what software they want to use with Postfix, be it anti-virus or otherwise.
There is one major problem with anti-virus software: It needs updating. Users cannot be relied upon to have even the anti-virus software in the first place, let alone be able or willing to pay for the updates.