Gmail addresses

Source
9. Create unlimited disposable email addresses with Gmail
Take the following example:
That’s right, you can add one or more dots ANYWHERE between your username and send messages to that ‘new’ email. All of those messages will arrive to your old (without dots) email. Hard to explain without a picture. But somehow Google did find a way to do it…

Sometimes you may receive a message sent to an address that looks like yours but has a different number or arrangement of periods. While we know it might be unnerving if you think someone else’s mail is being routed to your account, don’t worry: both of these addresses are yours.
Gmail doesn’t recognize dots as characters within usernames, you can add or remove the dots from a Gmail address without changing the actual destination address; they’ll all go to your inbox, and only yours. In short:

• homerjsimpson@gmail.com = hom.er.j.sim.ps.on@gmail.com
• homerjsimpson@gmail.com = HOMERJSIMPSON@gmail.com
• homerjsimpson@gmail.com = Homer.J.Simpson@gmail.com

All these addresses belong to the same person. You can see this if you try to sign in with your username, but adding or removing a dot from it. You’ll still go to your account.