Too Much Spam And Duplicate Email Messages

1. Create a Gmail account, at  https://mail.google.com. (You will not have to actually use this account.)
   
   
2. Go to Gmail's Options menu by clicking the gearwheel icon at the upper right. Go to Mail settings.
   
   
3. At the top, click Forwarding and POP/IMAP.
   
   
4. In the top section, add as a forwarding address your preferred email address, and enable forwarding.
   
   That's the total setup. Now all you'll have to do is remember to give out a special address for each subscription that might give out your email address and generate spam.
   
   
5. To each such sender, create your own new email address, in this form:
   
         [email protected]
   
   For example, let's say you want to subscribe to the newsletter at wackybargains.com. You could give your address as [email protected].

You'll get the wackybargains newsletter, forwarded to your regular address from Gmail. But should you later want to stop mail using the +wackybargains address, you could easily filter it out, and you'd never see it. (Just use the "Create a filter" link at the top of the Inbox to filter all mail having "wackybargains" in the "To" line.)  

Downsides. The only downside (if you consider it as such) is that a few websites will not allow a plus sign in your email address. But in all other cases this trick will work beautifully.