我有几个在 Debian 上运行的 postfix 邮件服务器都存在同样的问题。因此我搭建了一个测试服务器，问题解决后将销毁该服务器。
我从 OS350 平台收到的错误消息是：
Diagnostic information for administrators:
Generating server: BN3PR0401MB1251.namprd04.prod.outlook.com
Receiving server: BN3PR0401MB1251.namprd04.prod.outlook.com
[email protected]
12/25/2017 1:54:53 PM - Server at BN3PR0401MB1251.namprd04.prod.outlook.com returned '550 5.4.316 Message expired, connection refused(Socket error code 10061)'
12/25/2017 1:44:34 PM - Server at 4ceps.net (37.233.123.20) returned '450 4.4.316 Connection refused [Message=Socket error code 10061] [LastAttemptedServerName=4ceps.net] [LastAttemptedIP=37.233.123.20:25] [BN3NAM01FT008.eop-nam01.prod.protection.outlook.com](Socket error code 10061)'
以下是 4ceps.net 的 SOA： 在此处输入图片描述
邮件服务器的 nslookup 显示： 名称：isp4ceps9d.4ceps.net 地址：37.233.123.20
nslookup 搜索 IP 地址得到的结果为： 20.123.233.37.in-addr.arpa 名称 = isp4ceps9d.4ceps.net。
postconf -n 给出：
alias_database = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
append_dot_mydomain = no
biff = no
body_checks = regexp:/etc/postfix/body_checks
broken_sasl_auth_clients = yes
compatibility_level = 2
content_filter = amavis:[127.0.0.1]:10024
dovecot_destination_recipient_limit = 1
greylisting = check_policy_service inet:127.0.0.1:10023
header_checks = regexp:/etc/postfix/header_checks
html_directory = /usr/share/doc/postfix/html
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
maildrop_destination_concurrency_limit = 1
maildrop_destination_recipient_limit = 1
mime_header_checks = regexp:/etc/postfix/mime_header_checks
mydestination = isp4ceps9d.4ceps.net, localhost, localhost.localdomain
myhostname = isp4ceps9d.4ceps.net
mynetworks = 127.0.0.0/8 [::1]/128
myorigin = /etc/mailname
nested_header_checks = regexp:/etc/postfix/nested_header_checks
owner_request_special = no
proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $sender_bcc_maps $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks $smtpd_sender_login_maps
readme_directory = /usr/share/doc/postfix
receive_override_options = no_address_mappings
recipient_delimiter = +
relay_domains = mysql:/etc/postfix/mysql-virtual_relaydomains.cf
relay_recipient_maps = mysql:/etc/postfix/mysql-virtual_relayrecipientmaps.cf
relayhost =
sender_bcc_maps = proxy:mysql:/etc/postfix/mysql-virtual_outgoing_bcc.cf
smtp_tls_exclude_ciphers = RC4, aNULL
smtp_tls_protocols = !SSLv2,!SSLv3
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
smtpd_client_message_rate_limit = 100
smtpd_client_restrictions = check_client_access mysql:/etc/postfix/mysql-virtual_client.cf
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_sasl_authenticated, permit_mynetworks, check_helo_access regexp:/etc/postfix/helo_access, reject_invalid_hostname, reject_non_fqdn_hostname, reject_invalid_helo_hostname, reject_unknown_helo_hostname, check_helo_access regexp:/etc/postfix/blacklist_helo
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject_rbl_client zen.spamhaus.org, check_recipient_access mysql:/etc/postfix/mysql-virtual_recipient.cf, check_recipient_access mysql:/etc/postfix/mysql-virtual_policy_greylist.cf
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_restriction_classes = greylisting
smtpd_sasl_auth_enable = yes
smtpd_sasl_authenticated_header = yes
smtpd_sasl_path = private/auth
smtpd_sasl_type = dovecot
smtpd_sender_login_maps = proxy:mysql:/etc/postfix/mysql-virtual_sender_login_maps.cf
smtpd_sender_restrictions = check_sender_access regexp:/etc/postfix/tag_as_originating.re , permit_mynetworks, permit_sasl_authenticated, check_sender_access mysql:/etc/postfix/mysql-virtual_sender.cf, check_sender_access regexp:/etc/postfix/tag_as_foreign.re
smtpd_tls_cert_file = /etc/postfix/smtpd.cert
smtpd_tls_exclude_ciphers = RC4, aNULL
smtpd_tls_key_file = /etc/postfix/smtpd.key
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_protocols = !SSLv2,!SSLv3
smtpd_tls_security_level = may
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
transport_maps = hash:/var/lib/mailman/data/transport-mailman, proxy:mysql:/etc/postfix/mysql-virtual_transports.cf
virtual_alias_domains =
virtual_alias_maps = hash:/var/lib/mailman/data/virtual-mailman, proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, proxy:mysql:/etc/postfix/mysql-virtual_email2email.cf
virtual_gid_maps = mysql:/etc/postfix/mysql-virtual_gids.cf
virtual_mailbox_base = /var/vmail
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf
virtual_transport = dovecot
virtual_uid_maps = mysql:/etc/postfix/mysql-virtual_uids.cf
postconf -M 给出：
...
smtp inet n - y - - smtpd
submission inet n - y - - smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o smtpd_client_restrictions=permit_sasl_authenticated,reject
smtps inet n - y - - smtpd -o syslog_name=postfix/smtps -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes -o smtpd_client_restrictions=permit_sasl_authenticated,reject
pickup unix n - y 60 1 pickup
cleanup unix n - y - 0 cleanup
qmgr unix n - n 300 1 qmgr
tlsmgr unix - - y 1000? 1 tlsmgr
rewrite unix - - y - - trivial-rewrite
bounce unix - - y - 0 bounce
defer unix - - y - 0 bounce
trace unix - - y - 0 bounce
verify unix - - y - 1 verify
flush unix n - y 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - y - - smtp
relay unix - - y - - smtp
showq unix n - y - - showq
error unix - - y - - error
retry unix - - y - - error
discard unix - - y - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - y - - lmtp
anvil unix - - y - 1 anvil
scache unix - - y - 1 scache
maildrop unix - n n - - pipe flags=DRhu user=vmail argv=/usr/bin/maildrop -d vmail ${extension} ${recipient} ${user} ${nexthop} ${sender}
uucp unix - n n - - pipe flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
ifmail unix - n n - - pipe flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman unix - n n - - pipe flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py ${nexthop} ${user}
dovecot unix - n n - - pipe flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${user}@${nexthop}
amavis unix - - - - 2 smtp -o smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o smtp_bind_address=
127.0.0.1:10025 inet n - n - - smtpd -o content_filter= -o local_recipient_maps= -o relay_recipient_maps= -o smtpd_restriction_classes= -o smtpd_client_restrictions= -o smtpd_helo_restrictions= -o smtpd_sender_restrictions= -o smtpd_recipient_restrictions=permit_mynetworks,reject -o mynetworks=127.0.0.0/8 -o strict_rfc821_envelopes=yes -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks -o smtp_send_xforward_command=yes -o disable_dns_lookups=yes
127.0.0.1:10027 inet n - n - - smtpd -o content_filter= -o local_recipient_maps= -o relay_recipient_maps= -o smtpd_restriction_classes= -o smtpd_client_restrictions= -o smtpd_helo_restrictions= -o smtpd_sender_restrictions= -o smtpd_recipient_restrictions=permit_mynetworks,reject -o mynetworks=127.0.0.0/8 -o strict_rfc821_envelopes=yes -o receive_override_options=no_unknown_recipient_checks,no_header_body_checks -o smtp_send_xforward_command=yes -o milter_default_action=accept -o milter_macro_daemon_name=ORIGINATING -o disable_dns_lookups=yes