Web poison
Here is another nice way to confuse Spam bots: It is called web poison. The idea is to post some bogus email addresses on your page that only Spam bots can see. The way to do that is to close the mailto: command right away with an </a> without giving real users the chance to click on it. It looks like this:

href="mail to:lds1@+++ATH0.net"
href="mailto:123456@yahho.com"
href="mailto:789012@yuhho.com"

Caution: Touchy Notation
Make sure, you don't have any blank or character between the
href=mailto:xxx@yyy.com and the /a otherwise your visitors can click on that mailto command!