postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
command_directory = /usr/sbin
config_directory = /etc/postfix
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, $mydomain,mail.$mydomain, www.$mydomain, ftp.$mydomain
mydomain = hkstrong.com
myhostname = mail.hkstrong.com
mynetworks = 192.168.20.90/28, 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
sample_directory = /usr/share/doc/postfix-2.6.6/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
unknown_local_recipient_reject_code = 550

MX已经解析了外网IP地址了， IP已经映射到 mail.hkstrong.com

telnet localhost 110
Trying ::1...
Connected to localhost.
Escape character is '^]'.
+OK Dovecot ready.
user testpostfix
+OK
pass test
-ERR [IN-USE] Couldn't open INBOX: Internal error occurred. Refer to server log for more information. [2013-09-05 16:18:41]
Connection closed by foreign host.