Who is marc, the default receiver of root mail in /etc/aliases? Is 'marc' some person in the Linux/Unix community? In `/etc/aliases` on a default centos install, the bottom line reads: # Person who should get root's email # root: marc Or is it just a random name?

This is an example, but it wasn’t picked out of thin air: `marc` is Marc Ewing, who created Red Hat Linux and wrote the initial version of the `/etc/aliases` file which ends up in CentOS.

The line is commented out, so it doesn’t have any effect; if you want to redirect email sent to root, it’s up to you to choose whatever recipient is appropriate, correct the line to take that into account, and uncomment it.