[Dovecot] Using MailDir but local messages still save in mbox format

[Mike Edwards]

I am using MailDir format for all my virtual users and it is working 
well.  However, if email comes in to a unix system user, it delivers in 
Mbox format.    This is mostly cron jobs that do this.    Mail addressed 
to my virtual users goes to the MailDir locations just fine.  None of 
these mailboxes have ever been created, they are just incorrect assumed 
addresses.   There should NEVER be any email to username at my.host.name 
because everything is virtual.

Does anyone know how to fix this?

Here is my config.

# 2.0.9: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-358.18.1.el6.x86_64 x86_64 CentOS release 6.4 (Final)
auth_debug = yes
auth_mechanisms = plain login cram-md5 ntlm
auth_verbose = yes
auth_verbose_passwords = plain
disable_plaintext_auth = no
listen = *
mail_location = maildir:~/Maildir
mail_privileged_group = mail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope 
encoded-character vacation subaddress comparator-i;ascii-numeric 
relational regex imap4flags copy include variables body enotify 
environment mailbox date
mbox_write_locks = fcntl
passdb {
   args = /etc/dovecot/conf.d/dovecot-sql.conf.ext
   driver = sql
}
plugin {
   autocreate = Trash
   autocreate2 = Spam
   autocreate3 = Drafts
   autocreate4 = Sent
   autocreate5 = Archives
   autosubscribe = Trash
   autosubscribe2 = Spam
   autosubscribe3 = Drafts
   autosubscribe4 = Sent
   autosubscrube5 = Archives
   sieve = ~/.dovecot.sieve
   sieve_before = /home/vmail/movespam.sieve
   sieve_dir = ~/sieve
}
protocols = imap pop3
service auth {
   unix_listener /var/spool/postfix/private/auth {
     group = postfix
     mode = 0660
     user = postfix
   }
   unix_listener auth-master {
     mode = 0600
     user = vmail
   }
}
ssl_ca = /etc/pki/dovecot/ca/dovecot.pem
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
ssl_cipher_list = HIGH:MEDIUM:+TLSv1:!SSLv2:+SSLv3
userdb {
   args = uid=vmail gid=vmail home=/home/vmail/%d/%n
   driver = static
}
protocol lda {
   auth_socket_path = /var/run/dovecot/auth-master
   log_path = /home/vmail/dovecot-deliver.log
   mail_plugins = " sieve sieve"
   postmaster_address = postmaster at zeus.deltatechnicalservices.com
}
protocol lmtp {
   mail_plugins = " sieve"
}
protocol imap {
   mail_plugins = autocreate
}
protocol sieve {
   managesieve_implementation_string = Dovecot Pigeonhole
}
protocol pop3 {
   pop3_uidl_format = %08Xu%08Xv
}