dovecot - May 2008 - Problem finding inbox and pam_authenticate failed problem

Testing installation of Dovecot.  Log is showing two errors.  Any ideas how to
fix this thing???

dovecot: May 07 05:19:06 Error: auth-worker(default): pam(Yoda,127.0.0.1):
pam_authenticate() failed: User not known to the underlying authentication
module
dovecot: May 07 05:21:48 Error: IMAP(Yoda): open() failed with mbox file
/var/mail/Yoda: Permission denied

Here's the dovecot.conf file

# 1.1.rc4: /usr/local/etc/dovecot.conf
base_dir: /var/run/dovecot/
log_path: /var/log/dovecot.log
info_log_path: /var/log/dovecot-info.log
protocols: imap imaps pop3 pop3s
listen(default): *:143
listen(imap): *:143
listen(pop3): *:10100
ssl_disable: yes
disable_plaintext_auth: no
login_dir: /var/run/dovecot//login
login_executable(default): /usr/local/libexec/dovecot/imap-login
login_executable(imap): /usr/local/libexec/dovecot/imap-login
login_executable(pop3): /usr/local/libexec/dovecot/pop3-login
verbose_proctitle: yes
first_valid_uid: 1000
last_valid_uid: 5000
mail_privileged_group: mail
mail_location: mbox:/var/empty:INBOX=/var/mail/%u:INDEX=MEMORY
mail_debug: yes
mbox_write_locks: fcntl
mbox_very_dirty_syncs: yes
mail_executable(default): /usr/local/libexec/dovecot/imap
mail_executable(imap): /usr/local/libexec/dovecot/imap
mail_executable(pop3): /usr/local/libexec/dovecot/pop3
mail_plugin_dir(default): /usr/local/lib/dovecot/imap
mail_plugin_dir(imap): /usr/local/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/local/lib/dovecot/pop3
auth default:
  debug: yes
  debug_passwords: yes
  passdb:
    driver: pam
  passdb:
    driver: passwd
  passdb:
    driver: shadow
  passdb:
    driver: passwd-file
    args: /usr/local/etc/dovecot.passdb
  userdb:
    driver: passwd
  userdb:
    driver: passwd-file
    args: /usr/local/etc/dovecot.passdb
  socket:
    type: listen
    master:
      path: /var/run/dovecot/auth-master
      mode: 384
      user: dovecot
      group: mail





     
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