企业级基础邮件系统架设-阿里云开发者社区

邮件系统可以算是目前比较麻烦的互联网应用。由于各种垃圾邮件的横行，ISP和其他的邮箱提供者对邮件都有着很多限制。要玩转邮件系统，对于DNS系统，openrelay，网络黑名单，垃圾邮件过虑等各种规则都需要有一定程度的了解。

这是一副经典的邮件收发的流程图，清晰的描述了整个邮件收发的过程

整体架构简介

本文基于postfix+cyrus-sasl+extmail+mysql来架设一个功能较为完整的企业级邮件系统。

笔者水平有限，有不对之处还请路过的高手不吝赐教

在MTA系统中，sendmaill由于其苦涩的配置文件，安全性，效率。。。更多的缺点就不一一道来了。。。现在用的比较多的MTA系统还是当属改良sendmail之后的postfix

而postfix是不支持认证功能的，需要借助saslauthd 认证框架，结合pam的认证功能实现用户的认证。

这里借助cyrus-sasl来进行用户的认证。 cyrus-sasl本身不支持mysql和ldap的，要结合mysql需要还借助courier-authlib库来实现mysql的虚拟用户认证。

最后用extmail这个开源免费的webmail来做一个网页接口，让邮件系统可以使用web的方式访问

整个实现的流程图

实现过程

step1：环境安装

首先要安装整个开发环境，此外postfix和其它组件还需要依赖以下几个包 tcl,tcl-devel,libart_lgpl,libart_lgpl-devel,libtool-ltdl,libtool-ltdl-devel,expect

为extmail实现服务还需要安装web服务，这里使用apache 这些包用yum安装即可

[root@mail ~]# yum install tcl tcl-devel libart_lgpl libart_lgpl-devel libtool-ltdl libtool-ltdl-devel expect httpd –y

step2：安装mysql

由于在编译安装postfix的时候要指定mysql的路径，所以先安装好mysql，这里用绿色安装的方式安装mysql

添加mysql用户和用户组

[root@mail ~]# groupadd -r mysql

[root@mail ~]# useradd -r -d /mysql/data -s /sbin/nologin -g mysql -M mysql

解压安装mysql

[root@mail ~]# tar xf mysql-5.5.22-linux2.6-i686.tar.gz -C /usr/local/

[root@mail local]# ln -sv mysql-5.5.22-linux2.6-i686 mysql

[root@mail mysql]# scripts/mysql_install_db --user=mysql --datadir=/mysql/data

在此之前不要忘记创建数据目录并把所属用户和用户组改为mysql 复制启动脚本和配置文件

[root@mail mysql]# cp support-files/mysql.server /etc/rc.d/init.d/mysqld

[root@mail mysql]# cp support-files/my-large.cnf /etc/my.cnf 加载头文件和库文件（关键，安装postfix需要读取相关库文件）

[root@mail mysql]# ln -sv /usr/local/mysql/include /usr/include/mysql

[root@mail mysql]# echo "/usr/local/mysql/lib/" > /etc/ld.so.conf.d/mysql.conf 添加mysql的PATH命令路径

[root@mail mysql]# vi /etc/profile PATH=$PATH:/usr/local/mysql/bin

[root@mail mysql]# . /etc/profile

step3：安装postfix 添加对应用户

[root@mail ~]# groupadd -g 1024 postfix

[root@mail ~]# useradd -g postfix -u 1024 -s /sbin/nologin -M postfix

[root@mail ~]# groupadd -g 1025 postdrop

[root@mail ~]# useradd -g postdrop -u 1025 -s /sbin/nologin -M postdrop

解压编译安装安装之前确保安装开发包时已经安装cyrus-sasl相关包

[root@mail ~]# tar xf postfix-2.9.1.tar.gz

[root@mail ~]# cd postfix-2.9.1

[root@mail postfix-2.9.1]# make makefiles 'CCARGS=-DHAS_MYSQL -I/usr/local/mysql/include -DUSE_SASL_AUTH -DUSE_CYRUS_SASL -I/usr/include/sasl -DUSE_TLS ' 'AUXLIBS=-L/usr/local/mysql/lib -lmysqlclient -lz -lm -L/usr/lib/sasl2 -lsasl2 -lssl –lcrypto'

[root@mail postfix-2.9.1]# make

[root@mail postfix-2.9.1]# make install

安装的时候会要求输入相关选项一般按照默认就行了，

html_directory: [no] /var/www/html/postfix 此选项可以指定apache的网页路径，可以通过web查看postfix帮助文档

添加SysV服务脚本

#!/bin/bash
#
# postfix Postfix Mail Transfer Agent
#
# chkconfig: 2345 80 30
# description: Postfix is a Mail Transport Agent, which is the program \
# that moves mail from one machine to another.
# processname: master
# pidfile: /var/spool/postfix/pid/master.pid
# config: /etc/postfix/main.cf
# config: /etc/postfix/master.cf

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

# Source networking configuration.
. /etc/sysconfig/network

# Check that networking is up.
[ $NETWORKING = "no" ] && exit 3

[ -x /usr/sbin/postfix ] || exit 4
[ -d /etc/postfix ] || exit 5
[ -d /var/spool/postfix ] || exit 6

RETVAL=0
prog=”postfix”

start() {
# Start daemons.
echo -n $”Starting postfix: ”
/usr/bin/newaliases >/dev/null 2>&1
/usr/sbin/postfix start 2>/dev/null 1>&2 && success || failure $”$prog start”
RETVAL=$?
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/postfix
echo
return $RETVAL
}

stop() {
# Stop daemons.
echo -n $”Shutting down postfix: ”
/usr/sbin/postfix stop 2>/dev/null 1>&2 && success || failure $”$prog stop”
RETVAL=$?
[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/postfix
echo
return $RETVAL
}

reload() {
echo -n $”Reloading postfix: ”
/usr/sbin/postfix reload 2>/dev/null 1>&2 && success || failure $”$prog reload”
RETVAL=$?
echo
return $RETVAL
}

abort() {
/usr/sbin/postfix abort 2>/dev/null 1>&2 && success || failure $”$prog abort”
return $?
}

flush() {
/usr/sbin/postfix flush 2>/dev/null 1>&2 && success || failure $”$prog flush”
return $?
}

check() {
/usr/sbin/postfix check 2>/dev/null 1>&2 && success || failure $”$prog check”
return $?
}

restart() {
stop
start
}

# See how we were called.
case “$1″ in
start)
start
;;
stop)
stop
;;
restart)
stop
start
;;
reload)
reload
;;
abort)
abort
;;
flush)
flush
;;
check)
check
;;
status)
status master
;;
condrestart)
[ -f /var/lock/subsys/postfix ] && restart || :
;;
*)
echo $”Usage: $0 {start|stop|restart|reload|abort|flush|check|status|condrestart}”
exit 1
esac

exit $?

step4：构建DNS服务

为了方便我就直接在本机安装dns服务了

[root@mail ~]# yum install bind –y

具体的dns配置步骤不再列出，这里给出的我配置

name.conf

lustlost.com.zone

172.16.zone

修改resolv.conf ，dns服务器为本机测试下MX解析

step6：安装dovecot作为MRA

[root@mail ~]# yum install dovecot –y

编辑/etc/dovecot.conf 修改protocol = imap pop3 service dovecot start 就OK了

step7：整合SASL实现虚拟用户认证

postfix本身没有SASL模块，需要整合cyrus-sasl来实现认证，而cyrus-sasl对mysql的认证功能比较简陋，所以还需要借助courier-authlib库和mysql交互。

而dovecot可以直接和mysql交互，而不需要借助于cyrus-sasl

整体的流程在本文开头的图中有详细的描述

先安装courier-authlib让cyrus-sasl更好的支持mysql

[root@mail ~]# tar xf courier-authlib-0.62.4.tar.bz2

[root@mail ~]# cd courier-authlib-0.62.4

[root@mail courier-authlib-0.62.4]# ./configure \
–prefix=/usr/local/courier-authlib \
–sysconfdir=/etc \
–without-authpam \
–without-authshadow \
–without-authvchkpw \
–without-authpgsql \
–with-authmysql \
–with-mysql-libs=/usr/local/mysql/lib \
–with-mysql-includes=/usr/local/mysql/include \
–with-redhat \
–with-authmysqlrc=/etc/authmysqlrc \
–with-authdaemonrc=/etc/authdaemonrc \
–with-mailuser=postfix \
–with-mailgroup=postfix \
–with-ltdl-lib=/usr/lib

[root@mail courier-authlib-0.62.4]# make&&make install

提供courier-authlib的SysV风格脚本，安装目录下有此脚本，cp过去就OK了

[root@mail courier-authlib-0.62.4]# cp courier-authlib.sysvinit /etc/rc.d/init.d/courier-authlib

加入服务列表并开机自启动

[root@mail courier-authlib-0.62.4]# chkconfig –add courier-authlib
[root@mail courier-authlib-0.62.4]# chkconfig !$ on

可以将库文件载入系统库

[root@mail courier-authlib-0.62.4]# echo “/usr/local/courier-authlib/lib/courier-authlib” > /etc/ld.so.conf.d/local.conf

[root@mail courier-authlib-0.62.4]# ldconfig

提供配置文件

[root@mail courier-authlib-0.62.4]# cp /etc/authdaemonrc.dist /etc/authdaemonrc
[root@mail courier-authlib-0.62.4]# cp /etc/authmysqlrc.dist /etc/authmysqlrc

编辑authmysqlrc修改以下内容（各个字段和extmail创建的数据库是相连的，所以都要按照extmail的数据库字段来修改）

注意指定好mysql.sock文件路径然后修改authdaemonrc让courier-authlib使用mysql来认证（courier-authlib单单只可以使用mysql，也可以使用ldap）

[root@mail ~]# service courier-authlib start 然后配置SASL来支持courier-authlib

step8：配置postfix支持SASL认证和虚拟用户

[root@mail ~]# grep -v “^#” /etc/postfix/main.cf | grep -v “^$”

######全局的配置项########
queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain,
mail.$mydomain, www.$mydomain, ftp.$mydomain
unknown_local_recipient_reject_code = 550
mynetworks = 127.0.0.0/8
debug_peer_level = 2
debugger_command =
PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
ddd $daemon_directory/$process_name $process_id & sleep 5
sendmail_path = /usr/sbin/sendmail
newaliases_path = /usr/bin/newaliases
mailq_path = /usr/bin/mailq
setgid_group = postdrop
html_directory = /var/www/html/postfix
manpage_directory = /usr/local/man
sample_directory = /etc/postfix
readme_directory = no
inet_protocols = ipv4

#####支持CYRUS-SASL认证配置项#####
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject_invalid_hostname,reject_non_fqdn_hostname,reject_unknown_sender_domain,reject_non_fqdn_sender,reject_non_fqdn_recipient,reject_unknown_recipient_domain,reject_unauth_pipelining,reject_unauth_destination
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain = $myhostname
smtpd_sasl_security_options = noanonymous
smtpd_sasl_application_name = smtpd
smtpd_banner = Welcome to our $myhostname ESMTP,Warning: Version not Available!

######虚拟用户配置项###########
virtual_mailbox_base = /var/mailbox
virtual_mailbox_maps = mysql:/etc/postfix/mysql_virtual_mailbox_maps.cf
virtual_mailbox_domains = mysql:/etc/postfix/mysql_virtual_domains_maps.cf
virtual_alias_domains =
virtual_alias_maps = mysql:/etc/postfix/mysql_virtual_alias_maps.cf
virtual_uid_maps = static:2525
virtual_gid_maps = static:2525
virtual_transport = virtual
maildrop_destination_recipient_limit = 1
maildrop_destination_concurrency_limit = 1

########磁盘配额配置项##############

message_size_limit = 14336000
virtual_mailbox_limit = 20971520
virtual_create_maildirsize = yes
virtual_mailbox_extended = yes
virtual_mailbox_limit_maps = mysql:/etc/postfix/mysql_virtual_mailbox_limit_maps.cf
virtual_mailbox_limit_override = yes
virtual_maildir_limit_message = Sorry, the user’s maildir has overdrawn his diskspace quota, please Tidy your mailbox and try again later.
virtual_overquota_bounce = yes

step9：整合extman到postfix

extman是extmail的一个管理组件

[root@mail ~]# tar xf extman-1.1.tar.gz

[root@mail ~]# cd extman-1.1/docs/

导入数据库

由于extmail很久不更新了，所以数据库脚本在新的mysql5.5上语法有点问题，vi打开数据库脚本修改。（在mysql5.1上没有问题）

：%s@TYPE=MyISAM@ENGINE=MyISAM@g

[root@mail docs]# mysql -uroot -p < extmail.sql

[root@mail docs]# mysql -uroot -p < init.sql

创建extman相关的数据库用户

mysql> grant all privileges on extmail.* to extmail@localhost identified by ‘extmail’;
Query OK, 0 rows affected (0.00 sec)

mysql> grant all privileges on extmail.* to extmail@127.0.0.1 identified by ‘extmail’;
Query OK, 0 rows affected (0.00 sec)

提供extman的配置文件

[root@mail docs]# cp mysql_virtual_* /etc/postfix/

step10：配置dovecot支持mysql认证

dovecot本身就支持mysql认证，所以直接配置就行

修改/etc/dovecot/conf.d/10-mail.conf 中邮件目录

mail_location = maildir:/var/mailbox/%d/%n/Maildir

修改/etc/dovecot/conf.d/auth-sql.conf中使用mysql验证用户的配置文件位置
passdb {
driver = sql
args = /etc/dovecot/dovecot-sql.conf
}
userdb {
driver = sql
args = /etc/dovecot/dovecot-sql.conf
}

然后创建/etc/dovecot/dovecot-sql.conf，配置如下

driver = mysql
connect = host=/tmp/mysql.sock dbname=extmail user=extmail password=extmail
default_pass_scheme = CRYPT
password_query = SELECT username AS user,password AS password FROM mailbox WHERE username = ‘%u’
user_query = SELECT maildir, uidnumber AS uid, gidnumber AS gid FROM mailbox WHERE username = ‘%u’

step11：安装extmail和extman

安装extmail

[root@mail ~]# tar xf extmail-1.2.tar.gz

[root@mail ~]# mkdir /var/www/extsuite -pv

[root@mail ~]# cp extmail-1.2 /var/www/extsuite/extmail -R

修改配置文件

[root@mail extmail]# vi webmail.cf

这里grep出来的配置太长了，主要修改这几项
SYS_USER_LANG = zh_CN
SYS_MAILDIR_BASE = /var/mailbox
SYS_MYSQL_USER = extmail
SYS_MYSQL_PASS = extmail
SYS_MYSQL_SOCKET = /tmp/mysql.sock
SYS_AUTHLIB_SOCKET = /usr/local/courier-authlib/var/spool/authdaemon/socket

其它的默认即可

而后修改extmail目录下cgi的属主为postfix

[root@mail extmail]# chown -R postfix.postfix /var/www/extsuite/extmail/cgi/

安装extman

[root@mail ~]# cp extman-1.1 /var/www/extsuite/extman -R

修改配置文件

[root@mail extman]# vi webman.cf

主要是下面这几项
SYS_MAILDIR_BASE = /var/mailbox
SYS_DEFAULT_UID = 1024

SYS_DEFAULT_GID = 1024
SYS_MYSQL_USER = extmail
SYS_MYSQL_PASS = extmail
SYS_MYSQL_SOCKET = /tmp/mysql.sock

而后修改extman目录下cgi的属主为postfix

[root@mail extman]# chown -R postfix.postfix /var/www/extsuite/extman/cgi/

step12：整合将extmail和extman整合进apache

extmail和extman都是基于perl脚本实现的，所以要开机apache的perl的cgi

而它还需要perl的Unix::syslogd功能，所以需要编译安装Unix::syslogd

[root@mail ~]# tar xf Unix-Syslog-1.1.tar.gz

[root@mail ~]# cd Unix-Syslog-1.1
[root@mail Unix-Syslog-1.1]# perl Makefile.PL

[root@mail Unix-Syslog-1.1]# make && make install

配置1个虚拟主机

加入如下配置
User postfix
Group postfix

<VirtualHost *:80>
ServerName mail.magedu.com
DocumentRoot /var/www/extsuite/extmail/html/
ScriptAlias /extmail/cgi /var/www/extsuite/extmail/cgi
Alias /extmail /var/www/extsuite/extmail/html

ScriptAlias /extman/cgi /var/www/extsuite/extman/cgi
Alias /extman /var/www/extsuite/extman/html
</VirtualHost>

step13：完结。。。。

OK ，浏览器输入地址