“Your address is similar but has more or fewer dots (.) or different capitalization.

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:
o homerjsimpson@gmail.com = hom.er.j.sim.ps.on@gmail.com
o homerjsimpson@gmail.com = HOMERJSIMPSON@gmail.com
o 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.

One last thing: Google Apps does recognize dots. If you’d like to have a dot in your username, please ask your domain administrator to add your preferred username as a nickname.”