The so called "experts" should know how to encode your e-mail address on your website so you don't have this problem but what I have found is that most of the websites are made by some rookie who has acquired a copy of DreamWeaver and has become a professional Flash Webpage designer overnight. There are website harvest programs that visit every website in the world recording e-mail addresses and domains. They then sell them to people who think you might read and/or buy something from them when you see this Spam e-mail.
More information to come later.