A pointless waste of space is the note companies tend to put on the bottom of their emails along the lines of "this email has been checked for viruses by..." It is pointless because only if the virus checker is bang up to date is that assurance of any use at all, and you have no way of knowing if it is - or indeed if it has been virus checked at all.
As a someone put it to me this week, it's a bit like saying "We doubt if you need to beware of the dog. If we have a dog."
The truth is that if there is a virus attached to the email that the senders system or your own protection did not pick up, it will do its worst to your computer before you know what's going on anyway. So what do we do?