By saying treat as an alias you’re telling Google that it’s your own address. The consequences of this choice are only minor.
- If you’ve told Google it is your address, then if you put this address as a “To” (or Cc, Bcc) address, Gmail will simply place a copy directly into your inbox.
- If you’ve told Google it isn’t your address (ie, it’s not an alias), then if you put this address as a “To” (or Cc, Bcc) address, Gmail will still send the email as outgoing mail, treating it no differently to any other address.