Say for example you are creating a new google email account, you decided that your email will have a dot in between to differentiate your family name from your first name, e.g. email@example.com. We can tell you this there is no need to put dots.
This is because gmail neglects all dots, i.e. if I send an email firstname.lastname@example.org, email@example.com will be able to receive it. Even if I send it to firstname.lastname@example.org, and email@example.com will still be able to receive it.
It is safe to say that the below statement is correct, unless proven wrong.
Not all email services are like that. Most email servers, example Microsoft and Yahoo, uses dots to differentiate their email. Safe to say that firstname.lastname@example.org is not the same email as email@example.com. But for Gmail, they are both the same.
More read up: