Many web users don’t understand the inevitable consequences of exposing their e-mail address on the web. Experienced web developers and website owners, however do. Thousands of spam bots tirelessly crawl the web to collect e-mail addresses exposed on websites, in blog comments and elsewhere. These addresses end up in databases sold to unsavory marketers, who bombard the owners’s inboxes with unsolicited mail.
Of course, spam is an increasingly complicated problem that can never be solved by the efforts of web developers alone. But don’t underestimate your own powers.

A List Apart: Graceful E-Mail Obfuscation