Вот что раскопал в поддержке гугла. Может кому-то еще поможет (в моменты пятничной паранойи).
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.