In an attempt to clarify complex functionality, SendGrid is upgrading the name of Whitelabel. A whitelabel is now generally called sender authentication. A domain whitelabel is now called domain authentication. A link whitelabel is now called link branding. An IP Whitelabel is now called reverse DNS.
To set up sender authentication, add DNS records to your hosting service. These DNS records associate your sending domain with SendGrid — when an inbox provider processes your email, they will see your domain instead of sendgrid.net. You can also set up sender authentication for the links in your email as well as dedicated IP addresses associated with your account (available with Pro level or higher accounts).