我有一台 Postfix 服务器，其 SMTP 监听端口 587，而外部邮件服务器（如 Gmail）无法访问该端口，因此当我从 GMail 向以下服务器发送电子邮件时，会收到此“邮件传递失败”信息[电子邮件保护]：
收件人服务器未接受我们的连接请求。了解更多信息https://support.google.com/mail/answer/7720 [mail.mydomain.tld 邮件服务器IP:（有趣的是这里没有港口！）套接字错误]
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From: Name Family <[email protected]>
Date: Mon, 4 Apr 2016 17:35:00 +0430
Message-ID: <CAB4H0ddCYD=FfL4JsZSoqJtsmNKew+v_5KFpKfCeeOb7GD6fxQ@mail.gmail.com>
Subject: Re: test
To: Name <[email protected]>
Content-Type: multipart/alternative; boundary=001a113d9e02ad7f4f052fa86217
另外，从外部 ISP 挖掘以检查 DNS 记录结果：
dig MX mydomain.tld：
;; ANSWER SECTION:
mydomain.tld. 21599 IN MX 10 mail.mydomain.tld.
然后，dig A mail.mydomain.tld结果：
;; ANSWER SECTION:
mail.mydomain.tld. 21599 IN A proper.ip.address
我能够在本地帐户之间的邮件服务器内发送和接收电子邮件，也可以发送到 GMail 等外部邮件服务器，但我无法从外部接收电子邮件。
我的 postfix 配置是：
# See /usr/share/postfix/main.cf.dist for a commented, more complete version
# Debian specific: Specifying a file name will cause the first
# line of that file to be used as the name. The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
readme_directory = no
# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_un$
myhostname = mydomain.tld
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = mydomain.tld, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = loopback-only
inet_protocols = all
Master.cf内容：
#
# Postfix master process configuration file. For details on the format
# of the file, see the master(5) manual page (command: "man 5 master" or
# on-line: http://www.postfix.org/master.5.html).
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
# ==========================================================================
587 inet n - - - - smtpd
#smtp inet n - - - 1 postscreen
#smtpd pass - - - - - smtpd
#dnsblog unix - - - - 0 dnsblog
#tlsproxy unix - - - - 0 tlsproxy
#submission inet n - - - - smtpd
# -o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#smtps inet n - - - - smtpd
# -o syslog_name=postfix/smtps
# -o smtpd_tls_wrappermode=yes
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#628 inet n - - - - qmqpd
pickup unix n - - 60 1 pickup
cleanup unix n - - - 0 cleanup
qmgr unix n - n 300 1 qmgr
#qmgr unix n - n 300 1 oqmgr
tlsmgr unix - - - 1000? 1 tlsmgr
rewrite unix - - - - - trivial-rewrite
bounce unix - - - - 0 bounce
defer unix - - - - 0 bounce
trace unix - - - - 0 bounce
verify unix - - - - 1 verify
flush unix n - - 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - - - - smtp
relay unix - - - - - smtp
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - - - - showq
error unix - - - - - error
retry unix - - - - - error
discard unix - - - - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - - - - lmtp
anvil unix - - - - 1 anvil
scache unix - - - - 1 scache
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent. See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
# lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
# mailbox_transport = lmtp:inet:localhost
# virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus unix - n n - - pipe
# user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
# Old example of delivery via Cyrus.
#
#old-cyrus unix - n n - - pipe
# flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
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}
netstat -tulpn：
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:8888 0.0.0.0:* LISTEN 2050/stunnel4
tcp 0 0 0.0.0.0:21976 0.0.0.0:* LISTEN 877/sshd
tcp 0 0 127.0.0.1:953 0.0.0.0:* LISTEN 907/named
tcp 0 0 127.0.0.1:51101 0.0.0.0:* LISTEN 2310/irssi
tcp 0 0 127.0.0.1:51102 0.0.0.0:* LISTEN 2292/rtorrent
tcp 0 0 0.0.0.0:51103 0.0.0.0:* LISTEN 2292/rtorrent
tcp 0 0 0.0.0.0:993 0.0.0.0:* LISTEN 879/dovecot
tcp 0 0 0.0.0.0:51106 0.0.0.0:* LISTEN 2324/python
tcp 0 0 0.0.0.0:51107 0.0.0.0:* LISTEN 2317/python
tcp 0 0 0.0.0.0:995 0.0.0.0:* LISTEN 879/dovecot
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN 963/mysqld
tcp 0 0 0.0.0.0:1194 0.0.0.0:* LISTEN 1027/openvpn
tcp 0 0 127.0.0.1:587 0.0.0.0:* LISTEN 11162/master
tcp 0 0 0.0.0.0:110 0.0.0.0:* LISTEN 879/dovecot
tcp 0 0 0.0.0.0:143 0.0.0.0:* LISTEN 879/dovecot
tcp 0 0 0.0.0.0:10000 0.0.0.0:* LISTEN 2224/perl
tcp 0 0 0.0.0.0:4433 0.0.0.0:* LISTEN 2317/python
tcp 0 0 0.0.0.0:21201 0.0.0.0:* LISTEN 656/vsftpd
iptables -L：
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT tcp -- anywhere anywhere tcp dpt:smtp ctstate NEW,ESTABLISHED
ACCEPT tcp -- anywhere anywhere tcp spt:smtp
ACCEPT tcp -- anywhere anywhere tcp spt:submission
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ACCEPT tcp -- anywhere anywhere tcp spt:smtp ctstate ESTABLISHED
ACCEPT tcp -- anywhere anywhere tcp dpt:submission
ACCEPT tcp -- anywhere anywhere tcp spt:submission
有人能帮助我吗？谢谢。
答案1
您的 Postfix 安装无疑配置为仅为本地用户发送和接收电子邮件。为了从 Internet 接收消息，Postfix 必须能够接收端口 25/tcp (SMTP) 和 465/tcp (SMTP over SSL) 上的连接。我不确定 GMail 最初是否尝试建立安全的 SMTP 连接 (465/tcp)，但 GMail 肯定使用端口 587/tcp (SUBMISSION) 仅接收来自最终用户的消息。请参阅这里了解这些端口之间的差异。
我想是执行dpkg-reconfigure --priority=low postfix和供应给向导的正确答案将允许 Postfix 从互联网接收消息。或者：
设置
inet_interfaces = all在/etc/postfix/main.cf。inet_interfaces = all在中
/etc/postfix/master.cf，注释该587服务并取消注释smtp、smtpd和服务：submissionsmtps# 587 inet n - - - - smtpd smtp inet n - - - 1 postscreen smtpd pass - - - - - smtpd submission inet n - - - - smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o smtpd_reject_unlisted_recipient=no # -o smtpd_client_restrictions=$mua_client_restrictions # -o smtpd_helo_restrictions=$mua_helo_restrictions # -o smtpd_sender_restrictions=$mua_sender_restrictions # -o smtpd_recipient_restrictions= -o smtpd_relay_restrictions=permit_sasl_authenticated,reject # -o milter_macro_daemon_name=ORIGINATING smtps inet n - - - - smtpd -o syslog_name=postfix/smtps -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes -o smtpd_reject_unlisted_recipient=no # -o smtpd_client_restrictions=$mua_client_restrictions # -o smtpd_helo_restrictions=$mua_helo_restrictions # -o smtpd_sender_restrictions=$mua_sender_restrictions # -o smtpd_recipient_restrictions= # -o smtpd_relay_restrictions=permit_sasl_authenticated,reject # -o milter_macro_daemon_name=ORIGINATING
使用外部诊断工具检查您的邮件服务器是否可通过端口 25/tcp、465/tcp 和 587/tcp 公开访问。我建议您使用http://mxtoolbox.com/diagnostic.aspx和http://dns.kify.com/。