在CentOS6 系统里为 postfix 配置外部smtp服务器发邮件

感谢erow。

1.yum update # 更新软件

2.hostname erow.org # 设置主机名

3.vi /etc/postfix/main.cf # 编辑 postfix 配置文件，设置 myhostname = anqun.org

4.yum install stunnel # 安装 stunnel 软件，目的是转发465端口数据

5.vi /etc/stunnel/stunnel.conf # 编辑 stunnel 配置文件，内容如下：
[smtp-tls-wrapper]
   accept = 11125
   client = yes
   connect = smtp.mxhichina.com:4656.vi /etc/rc.d/init.d/stunnel # 编辑 stunnel 启动配置文件，内容如下：
#!/bin/bash
   #
   # Init Script to run stunnel in daemon mode at boot time.
   #
   # Author: Riccardo Riva - RPM S.r.l.
   # Revision 1.0 - 2010 November, 11

   #====================================================================
   # Run level information:
   #
   # chkconfig: 2345 99 99
   # description: Secure Tunnel
   # processname: stunnel
   #
   # Run "/sbin/chkconfig --add stunnel" to add the Run levels.
   # This will setup the symlinks and set the process to run at boot.
   #====================================================================

   #====================================================================
   # Paths and variables and system checks.

   # Source function library
   . /etc/rc.d/init.d/functions

   # Check that networking is up.
   #
   [ ${NETWORKING} ="yes" ] || exit 0

   # Path to the executable.
   #
   SEXE=/usr/bin/stunnel

   # Path to the configuration file.
   #
   CONF=/etc/stunnel/stunnel.conf

   # Check the configuration file exists.
   #
   if [ ! -f $CONF ] ; then
   echo "The configuration file cannot be found!"
   exit 0
   fi

   # Path to the lock file.
   #
   LOCK_FILE=/var/lock/subsys/stunnel

   #====================================================================

   # Run controls:

   prog=$"stunnel"

   RETVAL=0

   # Start stunnel as daemon.
   #
   start() {
   if [ -f $LOCK_FILE ]; then
   echo "stunnel is already running!"
   exit 0
   else
   echo -n $"Starting $prog: "
   $SEXE $CONF
   fi

   RETVAL=$?
   [ $RETVAL -eq 0 ] && success
   echo
   [ $RETVAL -eq 0 ] && touch $LOCK_FILE
   return $RETVAL
   }

   # Stop stunnel.
   #
   stop() {
   if [ ! -f $LOCK_FILE ]; then
   echo "stunnel is not running!"
   exit 0

   else

   echo -n $"Shutting down $prog: "
   killproc stunnel
   RETVAL=$?
   [ $RETVAL -eq 0 ]
   rm -f $LOCK_FILE
   echo
   return $RETVAL

   fi
   }

   # See how we were called.
   case "$1" in
   start)
   start
   ;;
   stop)
   stop
   ;;
   restart)
   stop
   start
   ;;
   condrestart)
   if [ -f $LOCK_FILE ]; then
   stop
   start
   RETVAL=$?
   fi
   ;;
   status)
   status stunnel
   RETVAL=$?
   ;;
   *)
   echo $"Usage: $0 {start|stop|restart|condrestart|status}"
   RETVAL=1
   esac

   exit $RETVAL

   #--- End of file ---
7.chkconfig stunnel on # 启用 stunnel 服务

8.chmod +x /etc/init.d/stunnel # 为 stunnel 配置文件，添加执行权限

9.service stunnel start # 启动 stunnel 服务

10.mkdir /etc/postfix/sasl # 创建 sasl 目录

11.vi /etc/postfix/sasl/sasl_passwd # 创建邮箱账户登录信息配置文件，内容如下：
[localhost]:11125 postmaster@anqun.org:password
12.postmap /etc/postfix/sasl/sasl_passwd # 生成postfix密码配置文件

13.chmod 600 /etc/postfix/sasl/* # 为了保护smtp的登录信息，需要修改上边两个文件为root用户只读写

14.vi /etc/postfix/main.cf # 修改 /etc/postfix/main.cf 文件，修改 relayhost = [localhost]:11125 , 添加SMTP信息：
relayhost = [localhost]:11125

   #### SMTP
   # Enable SASL authentication
   smtp_sasl_auth_enable = yes
   # Disallow methods that allow anonymous authentication
   smtp_sasl_security_options = noanonymous
   # Location of sasl_passwd
   smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd
   # Enable STARTTLS encryption
   # smtp_tls_security_level = encrypt
   # Location of CA certificates
   smtp_tls_CAfile = /etc/ssl/certs/ca-bundle.crt
   smtp_generic_maps = hash:/etc/postfix/generic
15.因为多数免费邮箱限定发信人是登录名（如 postmaster@erwo.org），所以在 /etc/postfix/generic 文件里填写可能发信的地址，如：apache
apache postmaster@anqun.org16.postconf -e 'smtp_host_lookup = dns, native' # 设置postfix dns解析

17./etc/init.d/postfix restart # 重启postfix

18.tail /var/log/maillog # 如有错误，可查看日志

参考： https://randomcentos.wordpress.com/2015/04/21/installing-stunnel-client-on-centos-6-6/