[Dovecot] using dovecot in Asterisk imap storage

[Asmaa Ahmed]

Hello, 
I am trying to use postfix/dovecot as mail server to be the imap storage for my voicemail system.For that I installed postfix and dovecot and trying to follow the instructions in this post http://etel.wiki.oreilly.com/wiki/index.php?title=Storing_Voicemail_on_an_IMAP_server&printable=yes
I should add a master user for Asterisk to your IMAP server that has access to all user's mailboxes and as per the instructions, I should edit auth section in dovecot.conf which I can't find! Is there something wrong or should I add this section by myselfAlso I don't have dovecot.masterusers, should I create it?   
$/etc/dovecot$ /usr/sbin/dovecot -n# 2.0.19: /etc/dovecot/dovecot.conf# OS: Linux 3.2.0-31-virtual x86_64 Ubuntu 12.04.3 LTS mail_location = maildir:~/Maildirmanagesieve_notify_capability = mailtomanagesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date ihavepassdb {  driver = pam}plugin {  sieve = ~/.dovecot.sieve  sieve_dir = ~/sieve}protocols = imap pop3 sieveservice auth {  unix_listener /var/spool/postfix/private/dovecot-auth {    group = postfix    mode = 0660    user = postfix  }}ssl_cert = </etc/ssl/certs/dovecot.pemssl_cipher_list = ALL:!LOW:!SSLv2:ALL:!aNULL:!ADH:!eNULL:!EXP:RC4+RSA:+HIGH:+MEDIUMssl_key = </etc/ssl/private/dovecot.pemuserdb {  driver = passwd}protocol imap {  imap_client_workarounds = delay-newmail  mail_max_userip_connections = 10}protocol pop3 {  mail_max_userip_connections = 10  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh}protocol lda {  deliver_log_format = msgid=%m: %$  mail_plugins = sieve  postmaster_address = postmaster  quota_full_tempfail = yes  rejection_reason = Your message to <%t> was automatically rejected:%n%r}

Thanks.