Gmail Email Address Aliases

I came across an interesting feature of Gmail the other day.  Apparently you can add a little something extra to your e-mail address to better help your mail filters or just track who is selling your e-mail address.  To use this feature, simply add a '+string' to the 'username' portion of your address.  For example, if your e-mail address was, you could track your messages from by using in all your Amazon communication.  This would make it really easy to apply mail filters no matter what the sending address is (since some sending addresses can be pretty crazy).  Another nice "feature" is being able to track who is selling your e-mail address… though you still might not have much recourse.  If you'd like another variation that still delivers to your gmail Inbox, you can also use the domain  Not sure why you'd want to, but to each his own.