The E-Mail is required so you can reset your password, in case you forget it.
You will not receive any other E-Mails than for registration and password reset reasons.
Except, if you opt-in on information services in Settings, like notifications, when a new player requests membership for your team, and you are a team admin.
After registration, you will receive an E-Mail. Confirm your E-Mail, by klicking on the link in the E-Mail, before you try to login.
You can not login, if you don't confirm your account first.
The E-Mail can take up to a minute to arrive in your inbox, because the E-Mail Service that is used, is for free. (SendGrid)