Hello there, I'm curious to know what purpose the group named "mail" serves in linux. I notice that this is the group that owns the var/spool/mail directory. Why do they own it? Does this group have any users in it? One other thing I'm wondering is if you can change the ownership of /var/spool/mail from the mail group to, I dunno, say, the users group without any bad consequences? Thanx, Joe

I'm not really an expert, but I'll do my best to answer until someone who really knows comes along! I think I'm write though. Basically. Your mail server should not run as root. It is generally a big piece of software which is open to the internet and so has plenty of potential holes. So you want to have a non root user that the mail program runs at. This is often mail. If there is a bug in the mail transfer agent (MTA) then at least it is only mail who is compromised. However mail needs to deliver mail to mailboxes. As these should be private they should be owned by the individual user. You don't want anyone else to read your mail. But mail needs to deliver the mail somehow. And the way it is done is that the files in /var/spool/mail are owned by the user, but coowned by the mail group. Therefore mail (the user) who is a member of mail (the group) can deliver mail to all, but only the recipient can read them So you could change ownership to another group, but you would have to 1) Make sure mail was a member of this group and 2) Make sure there are no other members of the group. And so, what is the best name for a group where mail is the only member? Of course, its mail! Now other MTAs can do something entirely different. The one that jumps into my head is qmail, which assigns a different user for each of the tasks that an MTA has to do.