OS:Ubuntu 11.10 64bit
インストールしたパッケージ:postfix,sasl2-bin,mail-stack-delivery,dovecot-common,dovecot-pop3d,dovecot-imapd
バージョン:postfix 2.8.5-2~build1,dovecot-common 1:2.0.13-1ubuntu3.2

上記のような環境でメールサーバを構築しているのですが、メールの送信は出来るのですが、外部からのメールの受信が出来ません。ポートは110番と143番をあけていて、ポートチェックをするとポートフォワードは出来ています。

エラーログを確かめてみましたが、エラーメッセージが出ず、手がかりがつかめていませんのでこちらで質問させていただきました。

以下は、Postfixの設定です。

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
body_checks = regexp:/etc/postfix/body_checks
broken_sasl_auth_clients = yes
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/lib/postfix
data_directory = /var/lib/postfix
header_checks = regexp:/etc/postfix/header_checks
home_mailbox = Maildir/
inet_interfaces = all
local_recipient_maps = unix:passwd.byname $alias_maps
mail_owner = postfix
mailbox_size_limit = 1073741824
mailq_path = /usr/bin/mailq
message_size_limit = 10485760
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mydomain = myzuxnet.dip.jp
myhostname = ubuntu-os
mynetworks = 127.0.0.0/8 192.168.11.0/24
myorigin = $mydomain
newaliases_path = /usr/bin/newaliases
sendmail_path = /usr/sbin/postfix
setgid_group = postdrop
smtpd_banner = $myhostname ESMTP $mail_name (@@DISTRO@@)
smtpd_client_restrictions = permit_mynetworks,reject_unknown_client,permit
smtpd_recipient_restrictions = permit_mynetworks,permit_auth_destination,permit_sasl_authenticated,reject
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = $myhostname
smtpd_sasl_path = private/auth-client
smtpd_sasl_security_options = noanonymous
smtpd_sasl_type = dovecot
unknown_local_recipient_reject_code = 550

以下は、dovecotの設定です。

# 2.0.13: /etc/dovecot/dovecot.conf
# OS: Linux 3.0.0-16-generic x86_64 Ubuntu 11.10
auth_debug = yes
auth_debug_passwords = yes
auth_mechanisms = plain login
disable_plaintext_auth = no
log_path = /var/log/dovecot.log
mail_debug = yes
mail_location = maildir:~/Maildir
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
passdb {
  driver = pam
}
plugin {
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
}
protocols = imap pop3 sieve
service auth {
  unix_listener /var/spool/postfix/private/auth-client {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener /var/spool/postfix/private/dovecot-auth {
    group = postfix
    mode = 0660
    user = postfix
  }
}
ssl = no
ssl_cert = </etc/ssl/certs/dovecot.pem
ssl_cipher_list = ALL:!LOW:!SSLv2:ALL:!aNULL:!ADH:!eNULL:!EXP:RC4+RSA:+HIGH:+MEDIUM
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
  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
}

他の情報が必要であれば順次いっていただければ掲載します。
ご教授願えませんでしょうか。