Centos搭建邮件服务器

前言

由于公司zabbix 监控告警邮件发送量过打，使用的腾讯企业邮箱会出现漏发或发送频率过快而拒绝发送的情况，所以现在使用自主搭建的内网邮件服务器来负责zabbix告警邮件的发送。

内网的告警邮件服务器只能给其他(腾讯企业邮箱，网易邮箱等)邮箱发送邮件，而不能接受其他邮箱的回邮件，如想可以收到回件需要购买域名配置A记录和MX记录，本文档不再讲解。

一 配置内网dns A记录和MX记录

我在内网使用的域名主机是dnsmasq代理软件，其使用简单，方便，多样化。详细配置可查看其他文档。

[root@dns_proxy ~]# grep liqing /etc/dnsmasq.conf
address=/mail.liqing-test.top/192.168.2.100
mx-host=liqing-test.top,mail.liqing-test.top,10

二 mail服务器初始化配置

1. 修改主机名

[root@localhost /]# hostnamectl --static set-hostname mail.liqing-test.top|bash

2. 关闭防火墙与selinux

[root@mail /]# systemctl stop iptables && systemctl disable iptables
[root@mail /]# systemctl stop firewalld && systemctl disable firewalld
[root@mail /]# setenforce 0

3. 开启时间同步

[root@mail /]# yum -y install ntpdate && ntpdate ntp.aliyun.com

4. 安装软件

[root@mail /]# yum  -y  install  postfix  dovecot  cyrus-sasl-*  mailx

三 修改配置文件

注释：配置文件备份操作本文档自行操作

1 配置postfix

[root@mail /]# cat /etc/postfix/main.cf
mail_owner = postfix
myhostname = mail.liqing-test.top
mydomain = liqing-test.top
myorigin = $mydomain
inet_interfaces = all
inet_protocols = ipv4
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain, mail.$mydomain, www.$mydomain, ftp.$mydomain
local_recipient_maps =
mynetworks = 0.0.0.0/0
relay_domains = $mydestination
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
smtpd_banner = $myhostname ESMTP

# 在最下面新增
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_local_domain =
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks,permit_auth_destination,permit_sasl_authenticated
smtpd_client_restrictions = permit_sasl_authenticated

2 配置dovecot

2.1 配置监听协议:

[root@mail /]# cat /etc/dovecot/dovecot.conf
protocols = imap pop3 lmtp
listen = *
login_trusted_networks = 0.0.0.0/0
dict {
}
!include conf.d/*.conf
!include_try local.conf

2.2 配置登录方式：

[root@mail /]# cat /etc/dovecot/conf.d/10-auth.conf
disable_plaintext_auth = no
auth_mechanisms = plain login
!include auth-system.conf.ext

2.3 配置邮件存储位置：

[root@mail /]# cat /etc/dovecot/conf.d/10-mail.conf
mail_location = mbox:~/mail:INBOX=/var/mail/%u
namespace inbox {
inbox = yes
}
first_valid_uid = 1000
mbox_write_locks = fcntl

[root@mail /]# cat /etc/dovecot/conf.d/10-master.conf 
service auth {
   unix_listener /var/spool/postfix/private/auth {
   mode = 0666
   user = postfix
   group = postfix
   }
}

2.4 配置ssl(关闭):

[root@mail /]# cat /etc/dovecot/conf.d/10-ssl.conf 
ssl = no

3 配置sasl2

3.1 配置系统认证：

[root@mail /]# cat /etc/sysconfig/saslauthd 
SOCKETDIR=/run/saslauthd
MECH=shadow
FLAGS=

3.2 配置登录方式:

[root@mail /]# cat /etc/sasl2/smtpd.conf
pwcheck_method: saslauthd
mech_list: PLAIN LOGIN
log_level:3

4 启动服务:

systemctl  restart  dovecot
systemctl  restart  postfix
systemctl  restart  saslauthd
systemctl  enable dovecot
systemctl  enable  postfix
systemctl  enable  saslauthd

5 创建用户并设置pass

[root@mail /]# useradd -m autumn && echo 123456 | passwd --stdin autumn
[root@mail /]# su - autumn 
[autumn@mail ~]$ mkdir -p ~/mail/.imap/INBOX
[autumn@mail ~]$ chmod -R 750 ~/mail        #(这不操作不做会在使用foxmail登录时报错{Error: Couldn't open INBOX: Permission denied})
[autumn@mail ~]$ exit

6 配置mailx：

[root@mail /]# cat /etc/mail.rc
set from=autumn@liqing-test.top
set smtp=mail.liqing-test.top
set smtp-auth-user=autumn
set smtp-auth-password=123456
set smtp-auth=login

四 发送邮件测试

1 命令行发送邮件测试

[root@mail /]# echo  "邮件服务器测试"  |  mail  -s  "邮件服务器测试"  other-email@163.com

2 使用使用foxmail登录并发送邮件测试

五 报错

1 权限被拒绝

在使用foxmail登录邮箱时提示权限被拒绝，这是因为在邮箱用户的家目录下mail文件权限不是750，设置为750后解决。

[autumn@mail ~]$ chmod -R 750 ~/mail

Dec 3 10:15:35 Git-server dovecot: pop3-login: Login: user=<autumn>, method=PLAIN, rip=192.168.31.100, lip=192.168.2.100, mpid=24843, secured, session=<YnZ3ezTSjiLAqB9k>

Dec 3 10:15:35 Git-server dovecot: pop3(autumn): Error: fchown(/home/autumn/mail/.imap, group=12(mail)) failed: Operation not permitted (egid=1004(autumn), group based on /var/mail/autumn - see http://wiki2.dovecot.org/Errors/ChgrpNoPerm)

Dec 3 10:15:35 Git-server dovecot: pop3(autumn): Error: Couldn't open INBOX: Permission denied

Dec 3 10:15:35 Git-server dovecot: pop3(autumn): Couldn't open INBOX: Permission denied top=0/0, retr=0/0, del=0/0, size=0

Dec 3 10:16:26 Git-server dovecot: pop3-login: Login: user=<autumn>, method=PLAIN, rip=192.168.31.100, lip=192.168.2.100, mpid=24895, secured, session=<NkWHfjTS2CLAqB9k>

Dec 3 10:16:26 Git-server dovecot: pop3(autumn): Error: fchown(/home/autumn/mail/.imap, group=12(mail)) failed: Operation not permitted (egid=1004(autumn), group based on /var/mail/autumn - see http://wiki2.dovecot.org/Errors/ChgrpNoPerm)

2 无法找到主机：

邮件在发送时会根据邮件地址的解析记录去查找mx记录，这里我在向腾讯的企业邮箱发送测试邮件时找不到腾讯的邮箱地址。我在内网的dns代理中加入了腾讯的mx记录后解决

[root@dns- ~]# grep qq /etc/dnsmasq.conf 
mx-host=***.com,mxbiz2.qq.com,10
mx-host=***.com,mxbiz1.qq.com,5

Dec 3 10:36:14 Git-server postfix/smtpd[26216]: connect from unknown[192.168.31.100]

Dec 3 10:36:15 Git-server postfix/smtpd[26216]: 05C682267F04: client=unknown[192.168.31.100], sasl_method=LOGIN, sasl_username=autumn

Dec 3 10:36:15 Git-server postfix/cleanup[26220]: 05C682267F04: message-id=<202112031036171922345@liqing-test.top>

Dec 3 10:36:15 Git-server postfix/qmgr[25430]: 05C682267F04: from=<autumn@liqing-test.top>, size=1561, nrcpt=1 (queue active)

Dec 3 10:36:15 Git-server postfix/smtpd[26216]: disconnect from unknown[192.168.31.100]

Dec 3 10:36:15 Git-server postfix/smtp[26221]: 05C682267F04: to=<***@***.com>, relay=none, delay=0.11, delays=0.08/0.02/0/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=***.com type=MX: Host not found, try again)

3 邮件被拒绝

在我向腾讯企业邮箱发送测试邮件时日志里出现了550邮件连接被拒绝的情况，此情况在邮件中设置白名单后解决。

Dec 3 10:11:57 Git-server postfix/smtpd[24617]: connect from mail.liqing-test.top[192.168.2.100]

Dec 3 10:11:57 Git-server postfix/smtpd[24617]: 4E2292267F04: client=mail.liqing-test.top[192.168.2.100], sasl_method=LOGIN, sasl_username=autumn

Dec 3 10:11:57 Git-server postfix/cleanup[24621]: 4E2292267F04: message-id=<61a97cec.xRtXn6hYj3NI3wI3%autumn@liqing-test.top>

Dec 3 10:11:57 Git-server postfix/qmgr[24504]: 4E2292267F04: from=<autumn@liqing-test.top>, size=541, nrcpt=1 (queue active)

Dec 3 10:11:57 Git-server postfix/smtpd[24617]: disconnect from mail.liqing-test.top[192.168.2.100]

Dec 3 10:11:58 Git-server postfix/smtp[24622]: 4E2292267F04: to=<***@***.com>, relay=mxbiz1.qq.com[183.57.48.34]:25, delay=1.6, delays=0.09/0.03/0.16/1.3, dsn=5.0.0, status=bounced (host mxbiz1.qq.com[183.57.48.34] said: 550 Mail content denied. http://service.exmail.qq.com/cgi-bin/help?subtype=1&&id=20022&&no=1000726 (in reply to end of DATA command))