Here is a cool free feature of Avast Free edition. You can scan the emails you get from an IMAP server, usually port 993 with Avast. What Avast does is to act as the conduit for that port.
Here is what I mean. Usually I use Google for my email through their Google Apps. When I set up email, I have to set it up going over a secure protocol through port 993. See screen shot below:
Now, change the settings in your email client (I am using Mozilla Thunderbird) to use the standard port of 143 and no encryption. See below:
Now open up AVAST, and then go to the Mail Shield, the Expert Settings, and then click on SSL Accounts. You will see that it is doing the 993 port for you and scanning your email for viruses --- Pretty cool and all for free!