» Don't post your email address on message boards or mailing list.
» Maintain two separate email aliases - one for business and important email and other one for subscribing to mailing lists and web forums (called throw away email)
» Don't publish your email addres directly on the homepage - use Email Obfuscators.
» Provide a fake email address to websites that require mandatory registration before you download software or read their archives.
While some of the approaches may work for you, they also tend to increase the workload - how would you keep a track of so many email addresses ? Or you may miss participating in a useful discussion mailing list because your fear that others will know your email id. So what is the workaround ?
One of latest techniques to prevent spam is by creating a disposable email address that stays active just for a pre-defined period and then expires. All the junk email sent to this disposable email address, after it has expired, will bounce back to the spammer.
I like the above approach for two reasons. One it works with my existing web email address without requiring me to signup for a separate email account. Second if I am suspicious that some website or newsletter would begin to spam me if I supply them my email address, I can first test their credibility using this disposable email.
If they spam, I will receive the spam for few days until the email address expires. If my fears are mistaken and they don't spam, I can signup with them using my main email address.
There are two free services, SpamBox and Mailexpire, that let you create temporary email address which expire after a given time. The spam email will still be directed to your primary email inbox but that would stop once the temporary account expires.
Here's a practical application of this technique - you need to register on a forum that requires e-mail verification, so you generate a spambox e-mail with an expiry of one hour. The generated e-mail will expire in an hour, way enough for the Forum to send you the verification code.
Stop creating throw away email addresses and generously share you [temporary] email address on the internet. Let spammers come and steal them.
How to Hide Email Address on Webpages ?
How Email Spammers Trick GMail Spam Filters ?