In using some of the antivirus programs, part of the trick of getting them to do what you want them to do is to configure them correctly. You need to carefully go through the options and check if you want email scanning on or not. I know that Norton Antivirus is that way.

As I recall from your previous posts, you have a McAfee product. I haven't used theirs in about two years, so am not sure how their current products work. But if you take some time and read the instructions for the program, I'll bet you can configure it the way you want. Should there be some additional options in it that you don't understand, I'm sure someone here will be able to help, as long as you have tried figuring it out by reading through McAfee instructions first.