Mail file on typical Linux install

Been running Linux for years, but never really paid any attention to the internal mail and mail files on my distribution since I have an external web host and run my POP mail through there.

But now I want to automate reading all the mail coming into the root account (from failed cron jobx, etc.) using Perl and Mail::Box and Mail::Box::Manager. When I try to use Mail::Box::Manager to open the mail at location $MAIL (shell environment -- or $ENV{MAIL} in Perl), it keeps saying I need to specify the folder. The examples I have in Perl for Mail::Box don't show a folder is need to open, nor do specify a folder I when I open mail in the shell ($ mail); I just see the mail.

In the shell when I say 'echo $MAIL' I get '-var-spool-mail-root' as the return value. Is this the same as an mbox? I don't think so. I think I've seen an 'mbox' folder or '.mbox' folder in some Unix accounts I have in other places. I need to know what kind of mail is this and I'm not sure how to determine this. I've been a Unix user for years, but I've never paid any attention to mail on Unix systems because I've never needed to.

c.l.p.m, sorry for the cross-post. I realize this is not technically a Perl issue, but maybe there is some nuance with Mail::Box::Manager that I am missing. This seems to me like this should be straight forward. The Perl code that comes back undefined is:

#!-usr-bin-perl $++;

use strict; use warnings qw( all );

use Data::Dumper; use Mail::Box::Manager;

print Dumper( $folder ); ## $folder comes back undef

## $ENV{MAIL} eq '-var-spool-mail-root'

Thanks, -ceo