Looking through my logs the other day, I noticed a lot of useragents "EmailSiphon". So I did a little research and found out that these things are ####ing email addresses from my webpages. I would presume they're taking them from the forums as well as they tend to ignore any robot.txt.
Anybody found an easy to implement solution that won't mess with searchengine spiders? I may write something in PHP for when my whole site is done over, but till then is there anything out there?