我正在尝试让虚拟托管的 PHP 网站在正确填写并提交网站的联系表单后向特定的 Gmail 地址发送电子邮件。不幸的是，什么都没有发送。/var/log/mail.log我遇到过很多类似这样的情况：
Jul 31 16:38:51 picus sm-mta[28576]: v6SL4xII018234: to=<[email protected]>,
delay=2+23:33:52, xdelay=00:00:00, mailer=esmtp, pri=38910659,
relay=mail.example.com., dsn=4.0.0, stat=Deferred:Connection refused by
mail.example.com.
我对处理电子邮件服务器完全陌生，只是想使用 Sendmail，因为它内置于我使用的发行版中，并且 Swiftmailer 支持它，所以我不知道如何解决这个问题。
我的sendmail.mc文件如下所示：
divert(-1)dnl
#-----------------------------------------------------------------------------
# $Sendmail: debproto.mc,v 8.14.4 2014-10-02 17:54:06 cowboy Exp $
#
# Copyright (c) 1998-2010 Richard Nelson. All Rights Reserved.
#
# cf/debian/sendmail.mc. Generated from sendmail.mc.in by configure.
#
# sendmail.mc prototype config file for building Sendmail 8.14.4
#
# Note: the .in file supports 8.7.6 - 9.0.0, but the generated
# file is customized to the version noted above.
#
# This file is used to configure Sendmail for use with Debian systems.
#
# If you modify this file, you will have to regenerate /etc/mail/sendmail.cf
# by running this file through the m4 preprocessor via one of the following:
# * make (or make -C /etc/mail)
# * sendmailconfig
# * m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
# The first two options are preferred as they will also update other files
# that depend upon the contents of this file.
#
# The best documentation for this .mc file is:
# /usr/share/doc/sendmail-doc/cf.README.gz
#
#-----------------------------------------------------------------------------
divert(0)dnl
#
# Copyright (c) 1998-2005 Richard Nelson. All Rights Reserved.
#
# This file is used to configure Sendmail for use with Debian systems.
#
define(`_USE_ETC_MAIL_')dnl
include(`/usr/share/sendmail/cf/m4/cf.m4')dnl
VERSIONID(`$Id: sendmail.mc, v 8.14.4-8 2014-10-02 17:54:06 cowboy Exp $')
OSTYPE(`debian')dnl
DOMAIN(`debian-mta')dnl
dnl # Items controlled by /etc/mail/sendmail.conf - DO NOT TOUCH HERE
undefine(`confHOST_STATUS_DIRECTORY')dnl #DAEMON_HOSTSTATS=
dnl # Items controlled by /etc/mail/sendmail.conf - DO NOT TOUCH HERE
dnl #
dnl # General defines
dnl #
dnl # SAFE_FILE_ENV: [undefined] If set, sendmail will do a chroot()
dnl # into this directory before writing files.
dnl # If *all* your user accounts are under /home then use that
dnl # instead - it will prevent any writes outside of /home !
dnl # define(`confSAFE_FILE_ENV', `')dnl
dnl #
dnl # Daemon options - restrict to servicing LOCALHOST ONLY !!!
dnl # Remove `, Addr=' clauses to receive from any interface
dnl # If you want to support IPv6, switch the commented/uncommentd lines
dnl #
FEATURE(`no_default_msa')dnl
dnl DAEMON_OPTIONS(`Family=inet6, Name=MTA-v6, Port=smtp, Addr=::1')dnl
DAEMON_OPTIONS(`Family=inet, Name=MTA-v4, Port=smtp, Addr=127.0.0.1')dnl
dnl DAEMON_OPTIONS(`Family=inet6, Name=MSP-v6, Port=submission, M=Ea, Addr=::1')dnl
DAEMON_OPTIONS(`Family=inet, Name=MSP-v4, Port=submission, M=Ea, Addr=127.0.0.1')dnl
dnl #
dnl # Be somewhat anal in what we allow
define(`confPRIVACY_FLAGS',dnl
`needmailhelo,needexpnhelo,needvrfyhelo,restrictqrun,restrictexpand,nobodyreturn,authwarnings')dnl
dnl #
dnl # Define connection throttling and window length
define(`confCONNECTION_RATE_THROTTLE', `15')dnl
define(`confCONNECTION_RATE_WINDOW_SIZE',`10m')dnl
dnl #
dnl # Features
dnl #
dnl # use /etc/mail/local-host-names
FEATURE(`use_cw_file')dnl
dnl #
dnl # The access db is the basis for most of sendmail's checking
FEATURE(`access_db', , `skip')dnl
dnl #
dnl # The greet_pause feature stops some automail bots - but check the
dnl # provided access db for details on excluding localhosts...
FEATURE(`greet_pause', `1000')dnl 1 seconds
dnl #
dnl # Delay_checks allows sender<->recipient checking
FEATURE(`delay_checks', `friend', `n')dnl
dnl #
dnl # If we get too many bad recipients, slow things down...
define(`confBAD_RCPT_THROTTLE',`3')dnl
dnl #
dnl # Stop connections that overflow our concurrent and time connection rates
FEATURE(`conncontrol', `nodelay', `terminate')dnl
FEATURE(`ratecontrol', `nodelay', `terminate')dnl
dnl #
dnl # If you're on a dialup link, you should enable this - so sendmail
dnl # will not bring up the link (it will queue mail for later)
dnl define(`confCON_EXPENSIVE',`True')dnl
dnl #
dnl # Dialup/LAN connection overrides
dnl #
include(`/etc/mail/m4/dialup.m4')dnl
include(`/etc/mail/m4/provider.m4')dnl
dnl #
dnl # Default Mailer setup
MAILER_DEFINITIONS
MAILER(`local')dnl
MAILER(`smtp')dnl
dnl # Masquerading options
FEATURE(`always_add_domain')dnl
MASQUERADE_AS(`debian')dnl
FEATURE(`allmasquerade')dnl
FEATURE(`masquerade_envelope')dnl
但是，我认为这可能是 DNS 问题，因为我无法通过端口 25 上的 telnet 连接到服务器。该端口似乎在我的 iptables 中是打开的：
$ sudo iptables -L -nv --line-numbers
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out source destination
1 0 0 DROP all -- * * 46.7.84.73 0.0.0.0/0
2 4047 304K fail2ban-ssh-ddos tcp -- * * 0.0.0.0/0 0.0.0.0/0 multiport dports 22
3 4926 376K fail2ban-recidive tcp -- * * 0.0.0.0/0 0.0.0.0/0
4 4048 304K fail2ban-ssh tcp -- * * 0.0.0.0/0 0.0.0.0/0 multiport dports 22
5 213 26142 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
6 0 0 REJECT all -- !lo * 127.0.0.0/8 0.0.0.0/0 reject-with icmp-port-unreachable
7 2 60 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW icmptype 8
8 26 1456 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 state NEW
9 14 816 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 state NEW
10 16 932 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:443 state NEW
11 0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:587 state NEW
12 4 240 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:25 state NEW
13 4903 378K ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
14 114 7692 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 limit: avg 5/min burst 5 LOG flags 0 level 7 prefix "iptables_INPUT_denied: "
15 130 13980 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
num pkts bytes target prot opt in out source destination
1 0 0 DROP all -- * * 46.7.84.73 0.0.0.0/0
2 0 0 LOG all -- * * 0.0.0.0/0 0.0.0.0/0 limit: avg 5/min burst 5 LOG flags 0 level 7 prefix "iptables_FORWARD_denied: "
3 0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable
Chain OUTPUT (policy ACCEPT 129 packets, 11501 bytes)
num pkts bytes target prot opt in out source destination
1 0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:587
2 105 15686 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:25
Chain fail2ban-recidive (1 references)
num pkts bytes target prot opt in out source destination
1 4926 376K RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
Chain fail2ban-ssh (1 references)
num pkts bytes target prot opt in out source destination
1 10 1276 REJECT all -- * * 91.197.232.103 0.0.0.0/0 reject-with icmp-port-unreachable
2 4038 303K RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
其结果$ netstat -tan | grep LISTEN | grep 127.0.0.1 | sort是：
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:443 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp6 0 0 :::443 :::* LISTEN
tcp6 0 0 :::80 :::* LISTEN
但结果$ netstat -tan | grep 25是
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN
它没有出现在第一组中，有什么原因吗？
答案1
我已确定该问题实际上是一个编程问题，具体来说就是 Swiftmailer 的问题。我服务器上的其他服务（OSSEC、fail2ban）发送电子邮件时没有问题，我甚至可以在通过 Symfony 控制台访问 Swiftmailer 时成功发送电子邮件。只有当我的控制器代码创建电子邮件并将其发送到邮件池时，才会出现问题。
为此，我将回答/关闭这个问题。如果有人足够了解 Swiftmailer 并愿意帮助我，我有一个在 Stack Overflow 上发帖关于它。