邮件系统搭建

1.安装DOVECOT IMAP 和 POP3 服务器

1.1安装 Dovecot

[root@iZoci4ddacn248Z ~]# dnf install dovecot
Last metadata expiration check: 2:29:35 ago on Sat 22 Feb 2025 10:06:04 AM CST.
Dependencies resolved.
=============================================================================================================
 Package                Architecture    Version                                     Repository          Size
=============================================================================================================
Installing:
 dovecot                x86_64          1:2.3.16-14.el9                             appstream          4.7 M
Installing dependencies:
 clucene-core           x86_64          2.3.3.4-42.20130812.e8e3d20git.el9          appstream          585 k
 libexttextcat          x86_64          3.4.5-11.el9                                appstream          209 k

Transaction Summary
=============================================================================================================
Install  3 Packages

Total download size: 5.5 M
Installed size: 20 M
Is this ok [y/N]: y
Downloading Packages:
(1/3): libexttextcat-3.4.5-11.el9.x86_64.rpm                                 1.7 MB/s | 209 kB     00:00    
(2/3): dovecot-2.3.16-14.el9.x86_64.rpm                                       15 MB/s | 4.7 MB     00:00    
(3/3): clucene-core-2.3.3.4-42.20130812.e8e3d20git.el9.x86_64.rpm            1.3 MB/s | 585 kB     00:00    
-------------------------------------------------------------------------------------------------------------
Total                                                                         13 MB/s | 5.5 MB     00:00     
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                     1/1 
  Installing       : libexttextcat-3.4.5-11.el9.x86_64                                                   1/3 
  Installing       : clucene-core-2.3.3.4-42.20130812.e8e3d20git.el9.x86_64                              2/3 
  Running scriptlet: dovecot-1:2.3.16-14.el9.x86_64                                                      3/3 
useradd warning: dovecot's uid 97 outside of the SYS_UID_MIN 201 and SYS_UID_MAX 999 range.

  Installing       : dovecot-1:2.3.16-14.el9.x86_64                                                      3/3 
  Running scriptlet: dovecot-1:2.3.16-14.el9.x86_64                                                      3/3 
  Verifying        : clucene-core-2.3.3.4-42.20130812.e8e3d20git.el9.x86_64                              1/3 
  Verifying        : dovecot-1:2.3.16-14.el9.x86_64                                                      2/3 
  Verifying        : libexttextcat-3.4.5-11.el9.x86_64                                                   3/3 

Installed:
  clucene-core-2.3.3.4-42.20130812.e8e3d20git.el9.x86_64            dovecot-1:2.3.16-14.el9.x86_64           
  libexttextcat-3.4.5-11.el9.x86_64                                

Complete!

[!NOTE]

如果 Dovecot 已安装，并且需要清理配置文件，请重命名或删除 /etc/dovecot/ 目
录。之后，重新安装软件包。在不删除配置文件的情况下，dnf reinstall dovecot
命令不会重置 /etc/dovecot/ 中的配置文件。

1.2.在 Dovecot 服务器上配置 TLS 加密

• 服务器证书：/etc/pki/dovecot/certs/server.example.com.crt
• 私钥：/etc/pki/dovecot/private/server.example.com.key
• 证书颁发机构(CA)证书：/etc/pki/dovecot/certs/ca.crt

cp gqliu.cn.key /etc/pki/dovecot/private/
cp DigiCert+Global+Root+G2.cer /etc/pki/dovecot/certs/
cp gqliu.cn_public.crt /etc/pki/dovecot/certs/

1.2.1 对私钥文件设置安全权限

chown root:root /etc/pki/dovecot/private/gqliu.cn.key 
chmod 600 /etc/pki/dovecot/private/gqliu.cn.key 

1.2.2 使用 Diffie-Hellman 参数生成文件

openssl dhparam -out /etc/dovecot/dh.pem 4096
Generating DH parameters, 4096 bit long safe prime

1.2.3 在 /etc/dovecot/conf.d/10-ssl.conf 文件中设置证书和私钥文件的路径

a. 更新 ssl_cert 和 ssl_key 参数，并将其设置为使用服务器的证书和私钥的路径：

ssl_cert = </etc/pki/dovecot/certs/gqliu.cn_public.crt
ssl_key = </etc/pki/dovecot/private/gqliu.cn.key

b. 取消 ssl_ca 参数的注释，并将其设置为使用 CA 证书的路径：

ssl_ca = </etc/pki/dovecot/certs/DigiCert+Global+Root+G2.cer

c. 取消 ssl_dh 参数的注释，并将其设置为使用 Diffie-Hellman 参数文件的路径：

ssl_dh = </etc/dovecot/dh.pem

[!IMPORTANT]

为确保 Dovecot 从文件中读取参数的值，该路径必须以 < 字符开头。

1.3.准备 Dovecot 以使用虚拟用户

1.3.1 创建 vmail 用户：

useradd --home-dir /var/mail/ --shell /usr/sbin/nologin vmail

1.3.2 仅将 /var/mail/ 的写权限授予 vmail 用户

chown vmail:vmail /var/mail/
chmod 700 /var/mail/

1.3.3 取消 /etc/dovecot/conf.d/10-mail.conf 文件中 mail_location 参数的注释，并将其设置为mailbox 格式和位置

echo "mail_location = sdbox:/var/mail/%n/" >> /etc/dovecot/conf.d/10-mail.conf

1.4 使用 PAM 作为 Dovecot 身份验证后端

1.4.1 在 /etc/dovecot/conf.d/auth-system.conf.ext 文件中，将 override_fields 参数添加到 userdb部分

sed -i '/^userdb {/a\  override_fields = uid=vmail gid=vmail home=/var/mail/%n/' /etc/dovecot/conf.d/auth-system.conf.ext

1.5 完成 Dovecot 配置

doveconf -n

1.5.1 启用并启动 dovecot 服务

systemctl enable --now dovecot

2.部署和配置 POSTFIX SMTP 服务器

禁用并删除 Sendmail 工具：

dnf remove sendmail

安装 Postfix：

dnf install postfix