1. can i have user maildirs to recite at other
than $HOME, say /var/spool/mail ?
You could, but you'll have to change a lot of thing.
And, there's really
no good reason for this.
Is there any reason from security point of view that
few people do not want to give their users $HOME ?
The mailserver I maintain delivers mail to $HOME/Maildir (using qmail),
and courier-IMAP has no trouble retrieving it from there.
I consider it more secure to deliver mail to the user's $HOME (though
I'd be reluctant to do it with NFS home directories for reliability
reasons) because of the innate security problems of sharing the
/var/spool/mail directory (or whichever one you otherwise deliver to).
However, using the maildir format substantially decreases those problems.
It is also easier to get all of a user's files if they are all in
one directory. This is something I notice because I used to work
at a company with two large sites far from each other; when someone
moved from one site to another, we had to move all of their files.
I would like to be able to keep crontab files in the home directory
as well, but haven't found (or really looked for) a good way to do
that.