Mailserver

Whenever I have new user or new site registered, I got email notifacation via my gmail address which I use when install WP. I thought things are doing well. But now I see on the Edit site page, there’s a Mailserver settings, it shows “mail.example.com”. Seems there’s another way to manage emails.

If I set up the Mailserver, all my mails will go to my email accounts that I set in the web hosting place, instead of going to my admin gmail address. Is this correct?

What’s the usage of the Mailserver when I already can recive emails via my gmail address?