[Dovecot] auth both system and virtual users

[Gerry Reno]

I haven't found a way for dovecot to manage the mail directory
ownership/permissions issue.  Here is how I solved it manually:
cd /var/mail
mkdir a b c d e f g h i j k l m n o p q r s t u v w x y z
chown root:mail ?
chmod 775 ?

/var/mail:
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 a
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 b
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 c
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 d
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 e
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 f
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 g
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 h
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 i
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 j
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 k
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 l
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 m
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 n
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 o
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 p
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 q
drwxrwxr-x 4 root  mail 4096 Oct 31 11:05 r
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 s
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 t
drwxrwxr-x 3 root  mail 4096 Oct 31 09:28 u
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 v
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 w
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 x
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 y
drwxrwxr-x 2 root  mail 4096 Oct 31 11:02 z


Now I can login as 'brichards' and it properly created the mail directories
under the 'r' directory.

/var/mail/r/brichards:
drwx------ 3 nfsnobody nfsnobody 4096 Oct 31 11:05 /var/mail/r/brichards/
drwx------ 5 nfsnobody nfsnobody 4096 Oct 31 11:05
/var/mail/r/brichards//Maildir
drwx------ 2 nfsnobody nfsnobody 4096 Oct 31 11:05
/var/mail/r/brichards//Maildir/cur
drwx------ 2 nfsnobody nfsnobody 4096 Oct 31 11:05
/var/mail/r/brichards//Maildir/new
drwx------ 2 nfsnobody nfsnobody 4096 Oct 31 11:05
/var/mail/r/brichards//Maildir/tmp

GR