On a UNIX machine, "root" is the name of the most godlike of all users, the one who can read, erase, or edit any file, who can run any program, who can sign up new users and terminate existing ones. So receiving a message from someone who has the account name "root" is like getting a letter from someone who has the title "President" or "General" on his letterhead. Randy’s been root on a few different systems, some of which were worth tens of millions of dollars, and professional courtesy demands he at least read this message.