I have always hated spam but compared to what others have told me about how much they receive everyday, I figured we were pretty lucky. We use MailWasher Pro located at www.firetrust.com to filter, sort and preview our mail before downloading it. This has always worked well for us.
If an email is suspicious we can view is safely in MailWasher to determine its legitimacy, then download or delete it. We used to blacklist email addresses with it as well but spam email is mostly cloaked and there is no reason to penalize an innocent mail server.
As of October 19th we were receiving about 70 spam emails per day, that was normal for us. Then we listed a mare on Craigslist, we got several serious inquiries on her or at least they seemed serious.
Some of the inquiries were just: "Is the mare still available?". When we answered them back, "Yes, she is still available.", we never heard anything from them again.
The flood gates were opened. As of today, we are receiving about 300 spam emails per day and climbing. These inquiries are nothing more than a way to get you to respond and reveal your email address. It is then put on a spam list as a current and active email address.
We thought that if we used Craigslist again, we would just list a phone number and say that we will not respond to emails but my Son listed an item on there and actually got a spam phone call. It's a dangerous world out there...