root@localhost libexec]# ls -ls /var/run/dovecot/
total 12
0 srwxrwxrwx 1 vmail vmail      0 Jun 27 23:20 auth-master
0 srw------- 1 vmail mail       0 Jun 28 14:54 auth-worker.20362
0 srwxrwxrwx 1 root  root       0 Jun 28 14:54 dict-server
8 drwxr-x--- 2 root  dovecot 4096 Jun 28 14:54 login
4 -rw------- 1 root  root       6 Jun 28 14:54 master.pid

postconf -n alias_database = hash:/etc/postfix/aliases alias_maps = $alias_database append_dot_mydomain = no biff = no broken_sasl_auth_clients = yes command_directory = /usr/sbin config_directory = /etc/postfix daemon_directory = /usr/libexec/postfix debug_peer_level = 2 disable_vrfy_command = no html_directory = no inet_interfaces = all mail_owner = postfix mail_spool_directory = /var/spool/mail mailbox_size_limit = 0 mailq_path = /usr/bin/mailq manpage_directory = /usr/share/man mydestination = $myhostname, localhost.$mydomain, $transport_maps mydomain = sale.domainxxx.vn myhostname = mail.sale.domainxxx.vn mynetworks = 127.0.0.0/8 myorigin = $myhostname newaliases_path = /usr/bin/newaliases queue_directory = /var/spool/postfix readme_directory = /usr/share/doc/postfix-2.2.10/README_FILES recipient_delimiter = + sample_directory = /usr/share/doc/postfix-2.2.10/samples sendmail_path = /usr/sbin/sendmail.postfix setgid_group = postdrop smtp_tls_note_starttls_offer = yes smtp_use_tls = yes smtpd_banner = $myhostname smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination smtpd_sasl_auth_enable = yes smtpd_sasl_authenticated_header = yes smtpd_sasl_local_domain = smtpd_sasl_path = ./dovecot-auth smtpd_sasl_security_options = noanonymous smtpd_sasl_type = dovecot smtpd_tls_CAfile = /etc/postfix/ssl/mailserver/cacert.pem smtpd_tls_key_file = /etc/postfix/ssl/mailserver/smtpd.key smtpd_tls_loglevel = 1 smtpd_tls_received_header = no smtpd_tls_session_cache_timeout = 3600s smtpd_use_tls = yes tls_random_source = dev:/dev/urandom unknown_local_recipient_reject_code = 450 virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf virtual_gid_maps = static:12 virtual_mailbox_base = /var/vmail virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf virtual_mailbox_limit_maps = mysql:/etc/postfix/mysql_virtual_mailbox_limit_maps.cf virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf virtual_minimum_uid = 150 virtual_transport = dovecot virtual_uid_maps = static:150 

# 1.0.7: /etc/dovecot.conf
base_dir: /var/run/dovecot/
log_path: /var/log/maillog
log_timestamp: %Y-%m-%d %H:%M:%S
protocols: imap pop3 imaps pop3s
login_dir: /var/run/dovecot/login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
first_valid_uid: 150
last_valid_uid: 150
mail_location: maildir:/var/vmail/%d/%n/Maildir
maildir_copy_with_hardlinks: yes
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugins(default):
mail_plugins(imap):
mail_plugins(pop3): quota
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
pop3_client_workarounds(default):
pop3_client_workarounds(imap):
pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
namespace:
  type: private
  separator: /
  inbox: yes
auth default:
  mechanisms: plain login
  default_realm: sale.domainxxx.vn
  user: vmail
  passdb:
    driver: sql
    args: /etc/dovecot-mysql.conf
  userdb:
    driver: sql
    args: /etc/dovecot-mysql.conf
  socket:
    type: listen
    client:
      path: /var/spool/postfix/dovecot-auth
      mode: 3
      user: vmail
      group: vmail

Bạn thử kiểm tra file: /etc/postfix/aliases và thêm # trước dòng: postfix: root Sau đó check lại mail thử. 

#tail -f /var/log/maillog Jun 28 15:07:21 localhost postfix/smtpd[20424]: warning: unknown[113.172.3.210]: SASL LOGIN authentication failed: UGFzc3dvcmQ6 deliver(test02@sdomainxxx.vn): 2012-06-28 15:07:21 Error: Can't connect to auth server at /var/run/dovecot/auth-master: Connection refused