带有 dovecot 的后缀 smtp-auth 无法进行身份验证

在 Centos 6.5 上我运行 postfix

postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
broken_sasl_auth_clients = yes
command_directory = /usr/sbin
config_directory = /etc/postfix
content_filter = amavisfeed:[127.0.0.1]:10024
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
debug_peer_level = 2
home_mailbox = Maildir/
html_directory = no
inet_interfaces = all
inet_protocols = all
mail_owner = postfix
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mydomain = itzena.cz
myhostname = server.itzena.cz
mynetworks = 127.0.0.0/8
myorigin = $mydomain
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.6.6/README_FILES
relay_domains = proxy:mysql:/etc/postfix/mysql-relay_domains_maps.cf
sample_directory = /usr/share/doc/postfix-2.6.6/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
smtp_tls_note_starttls_offer = yes
smtpd_recipient_restrictions = permit_sasl_authenticated,    permit_mynetworks,    reject_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_tls_security_options = noanonymous
smtpd_sasl_type = dovecot
smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem
smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt
smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key
smtpd_tls_received_header = yes
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:/var/spool/postfix/smtpd_tls_cache
smtpd_tls_session_cache_timeout = 3600s
unknown_local_recipient_reject_code = 550
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql-virtual_alias_maps.cf,                     regexp:/etc/postfix/virtual_regexp
virtual_gid_maps = static:12
virtual_mailbox_base = /home/vmail
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains_maps.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailbox_maps.cf
virtual_minimum_uid = 101
virtual_transport = dovecot
virtual_uid_maps = static:101

鸽舍

[root@server postfix]# dovecot -n
# 2.0.9: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-431.3.1.el6.x86_64 x86_64 CentOS release 6.5 (Final) ext4
debug_log_path = /var/log/dovecot/sieve.log
first_valid_gid = 12
first_valid_uid = 101
info_log_path = /etc/dovecot/conf.d/example.com/dovecot_deliver.log
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
mail_debug = yes
mail_gid = mail
mail_location = maildir:/home/vmail/%d/%n
mail_uid = vmail
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 {
  driver = pam
}
passdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
plugin {
  mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
  mail_log_fields = uid box msgid size
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
  sieve_global_path = /var/lib/dovecot/sieve/default.sieve
}
protocols = imap pop3 lmtp sieve
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0666
    user = postfix
  }
  unix_listener auth-userdb {
    group = mail
    mode = 0600
    user = vmail
  }
}
service imap-login {
  inet_listener imap {
    port = 143
  }
  inet_listener imaps {
    port = 993
    ssl = yes
  }
}
service imap {
  process_limit = 1024
}
service managesieve-login {
  inet_listener sieve {
    port = 4190
  }
}
service pop3-login {
  inet_listener pop3s {
    port = 995
    ssl = yes
  }
}
service pop3 {
  process_limit = 1024
}
ssl_cert = </etc/postfix/ssl/smtpd.crt
ssl_key = </etc/postfix/ssl/smtpd.key
userdb {
  driver = passwd
}
userdb {
  args = /etc/dovecot/dovecot-sql.conf.ext
  driver = sql
}
protocol lmtp {
  mail_plugins = " sieve"
}
protocol lda {
  mail_plugins = " sieve"
}
protocol sieve {
  mail_max_userip_connections = 10
}
[root@server postfix]#

但如果我从本地主机测试

[root@server postfix]# telnet localhost smtp
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 server.itzena.cz ESMTP Postfix
ehlo server.itzena.cz
250-server.itzena.cz
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH PLAIN
250-AUTH=PLAIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN