配置Postfix服务程序

配置Postfix服务程序

Postfix是一款由IBM集团出资研发的免费开源电子邮件服务程序，能够很好的兼容Sendmail服务程序，也就是说Sendmail用户可以很方便的迁移到新的服务上面，Postfix服务的收件、发件性能确实强过Sendmail服务，并且能够自动增加、减少进程的数量来保证电子邮件系统的高性能与稳定性，另外Postfix服务程序是由诸多的小模块组成，每个小模块都可以完成特定的功能，因此在今后的生产工作环境中可以灵活搭配它们。详情请关注《linux就该这么学》。

安装Postfix服务程序，当然这一步在红帽RHEL7系统中是多余的，刘遄老师把步骤写下来的目的是为了让同学们读完这本《Linux就该这么学》后不仅能够掌握红帽RHEL系统，还能立即上手fedora、centos等等主流的Linux系统，当那些系统没有Postfix服务程序的时候也不用慌~对了，最后记得把iptables防火墙给禁用掉，否则会导致外部用户访问不了咱们的电子邮件系统。

[root@linuxprobe ~]# yum install postfix

Loaded plugins: langpacks, product-id, subscription-manager

rhel7 | 4.1 kB 00:00

(1/2): rhel7/group_gz | 134 kB 00:00

(2/2): rhel7/primary_db | 3.4 MB 00:00

Package 2:postfix-2.10.1-6.el7.x86_64 already installed and latest versionNothing to do

[root@linuxprobe ~]# systemctl disable iptables

配置Postfix服务程序，对于初次看到Postfix服务程序主配置文件（/etc/postfix/main.cf）的同学一定会被吓到吧，竟然足足有679行左右呢，但其实不必担心，这里面绝大多数的内容依然是注释信息，而且刘遄老师一直在强调Linux系统正确的学习方法，负责任的好老师不应只是做书本的搬运工，更应该做一名优质内容的提炼者。

Postfix服务程序总共需要修改五处，首先是在约76行左右定义有一个名称为myhostname的变量，它用来保存服务器的主机名称，读者请记住这个变量的名称，下边参数需要调用它：

[root@linuxprobe ~] # vim /etc/postfix/main.cf

# INTERNET HOST AND DOMAIN NAMES

#

# The myhostname parameter specifies the internet hostname of this

# mail system. The default is to use the fully-qualified domain name

# from gethostname(). $myhostname is used as a default value for many# other configuration parameters.

#

#myhostname = host.domain.tld

myhostname = mail.linuxprobe.com

第二处是约83行左右定义有一个名称为mydomain的变量，用来保存邮件域的名称，同学们也要记住这个变量名称，下面来调用它：

# The mydomain parameter specifies the local internet domain name.

# The default is to use $myhostname minus the first component.

# $mydomain is used as a default value for many other configuration

# parameters.#

mydomain = linuxprobe.com

第三处是约99行左右调用前面的mydomain变量，用来定义寄出邮件的域，调用变量的好处是避免重复写入信息以及便于今后统一进行修改：

# SENDING MAIL

#

# The myorigin parameter specifies the domain that locally-posted

# mail appears to come from. The default is to append $myhostname,

# which is fine for small sites. If you run a domain with multiple

# machines, you should (1) change this to $mydomain and (2) set up

# a domain-wide alias database that aliases each user to

# user@that.users.mailhost.

#

# For the sake of consistency between sender and recipient addresses,

# myorigin also specifies the default domain name that is appended

# to recipient addresses that have no @domain part.

##myorigin = $myhostname

myorigin = $mydomain

第四处是约116行左右定义的网卡监听地址，您可以指定要由服务器的那些IP地址对外提供电子邮件服务，也可以干脆写成all，代表所有网卡都能向客户提供电子邮件服务：

# The inet_interfaces parameter specifies the network interface

# addresses that this mail system receives mail on. By default,

# the software claims all active interfaces on the machine. The

# parameter also controls delivery of mail to user@[ip.address].

#

# See also the proxy_interfaces parameter, for network addresses that

# are forwarded to us via a proxy or network address translator.

#

# Note: you need to stop/start Postfix when this parameter changes.

##inet_interfaces = all

#inet_interfaces = $myhostname

#inet_interfaces = $myhostname, localhost

inet_interfaces = all

最后第五处是约164行左右定义的可接收邮件的主机名或域名列表，此处可以直接调用前面两个定义好的myhostname，mydomain变量即可（当然不想调用变量，直接写名称信息的话也可以）：

# The mydestination parameter specifies the list of domains that this

# machine considers itself the final destination for.

#

# These domains are routed to the delivery agent specified with the

# local_transport parameter setting. By default, that is the UNIX

# compatible delivery agent that lookups all recipients in /etc/passwd

# and /etc/aliases or their equivalent.

#

# The default is $myhostname + localhost.$mydomain. On a mail domain

# gateway, you should also include $mydomain.

#

# Do not specify the names of virtual domains - those domains are

# specified elsewhere (see VIRTUAL_README).

#

# Do not specify the names of domains that this machine is backup MX# host for. Specify those names via the relay_domains settings for

# the SMTP server, or use permit_mx_backup if you are lazy (see

# STANDARD_CONFIGURATION_README).

#

# The local machine is always the final destination for mail addressed

# to user@[the.net.work.address] of an interface that the mail system

# receives mail on (see the inet_interfaces parameter).

#

# Specify a list of host or domain names, /file/name or type:table

# patterns, separated by commas and/or whitespace. A /file/name

# pattern is replaced by its contents; a type:table is matched when

# a name matches a lookup key (the right-hand side is ignored).

# Continue long lines by starting the next line with whitespace.

#

# See also below, section "REJECTING MAIL FOR UNKNOWN LOCAL USERS".

#mydestination = $myhostname, localhost.$mydomain, localhost

#mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain

mydestination = $myhostname, $mydomain

创建电子邮件系统的登陆帐号，Postfix与Vsftpd服务程序一样都可以调用本地系统帐号和密码，因此在本地进行常规帐号创建即可，最后再把配置妥当的postfix服务重启，加入到开机启动项中就大功告成了！~

[root@linuxprobe ~] # useradd boss

[root@linuxprobe~] # echo "linuxprobe" | passwd --stdin boss

Changing password for user boss. passwd: all authentication tokens updated successfully.

[root@linuxprobe~] # systemctl restart postfix

[root@linuxprobe~] # systemctl enable postfix

ln -s '/usr/lib/systemd/system/postfix.service' '/etc/systemd/system/multi-user.target.wants/postfix.service'