You may want to read this first. The original contents of this post moved to the first comment, since I have worked out an even better approach to combating spam with GMail. The idea is to create two email IDs with GMail (say firstname.lastname@example.org and email@example.com) – one real and the other “hidden”. The real one (abc) can be given to close friends who you trust not to spam. For all others do this: suppose you want to share your email ID with eBay.com and you dont trust eBay. Share this email ID with them: firstname.lastname@example.org. Setup a forwarder in ‘pqr’ account to forward all email sent to email@example.com to firstname.lastname@example.org. All other email in the ‘pqr’ (for example sent to email@example.com) account can be set to be autodeleted. You get all your email in the firstname.lastname@example.org account, without having to share it. More information on why this works is in the comment.
Why is this necessary? Why cant we work the same way as I mentioned earlier? Here is why: Spammers are also smart. Suppose you create an account email@example.com and share firstname.lastname@example.org. Now, spammers can search there database searching for gmail addresses with a ‘+’ in them and remove the ‘+’ and the part following it. Now what happens? You start getting spam at your real email ID with no way to filter it. If we change our tactics slightly, with what I suggest above, in such a scenario spammers will send email to email@example.com, which isnt getting forwarded. Do try and let me know pitfalls. I know its a bit complex but should be worth it – have questions, post comments.