MW checks any POP3 accounts you tell it about. It classifies the mail as Virus, Probably Spam, Possibly Spam, Normal, Blacklist or Friend and then sets options for each item of mail according to the classification. It does not carry out those actions until you tell it to by clicking Process Mail, then it bounces marked mail (the same sort of thing that happens when you send mail to an unknown address), deletes marked mail and starts your email client, eg Outlook Express for you. You download it from
http://www.mailwasher.net.
It is extremely simple to set up and there is extensive, simple to understand, help on the website.
I use it and I doubt you will want to uninstall it after using it, however you uninstall it through Controll Panel/ Add-Remove Programs.
It works with Dial Up/Cable/ADSL connections and any mail client. At the moment it does NOT handle IMAP, Hotmail or AOL accounts but the author is working on it. On the website there are 2 versions you can download. One of them is a beta version of the next release, but if you do not feel comfortable as a field tester then download the other one which is very stable (thats the one I use). Its free but Nick Boltan (the author) accepts donations to offset his costs. If you do have problems email him and you will usually get a reply within 24 hours.
Hope this helps
Geoff