Your GMail address has a near infinite number of variations!

Did you know that your GMail address can be extended?

It can be a fantastic way to uniquely identify which source that gave away your address to a spammer, but more importantly - it helps you to filter your mail!

Let's say my address is mymail@gmail.com and let's say that I want to sign up for a newsletter for something useful - like a site for Silly Walk GIFs, 

If I signup for the newsletter with mymail+SillyWalks@gmail.com- that is not only perfectly legal and working, it also means that the mail that arrives, hasmymail+SillyWalks@gmail.com in the To: field.

So:
mymail@gmail.com
mymail+ebay@gmail.com
mymail+NYPost@gmail.com
mymail+ScaryWebSite@gmail.com
i.e.
mymail+SomeRandomKeyword@gmail.com

are all working, valid addresses which are uniquely identifiable by you.