on systems with a postfix MTA and system user accounts
eg set in /etc/postfix/main.cf
home_mailbox = Maildir/
then add the followin to the end of /etc/Muttrc
set folder="~/Maildir" set mask="!^\\.[^.]" set mbox="~/Maildir" set record="+.Sent" set postponed="+.Drafts" set spoolfile="~/Maildir"
the user's mailboxes are in their home directories instead of /var/mail/mailuser and look like directory structures instead of flat files eg.
# ls /home/testuser/Maildir/ cur new tmp
partially true for debian wheezy links:
debian Maildir Configuration
debian postfix
mutt with postfix and Maildir