diff --git a/en_US/installation/0-install.iredmail.on.rhel.md b/en_US/installation/0-install.iredmail.on.rhel.md
index b3749bb8..d6b6f8ae 100644
--- a/en_US/installation/0-install.iredmail.on.rhel.md
+++ b/en_US/installation/0-install.iredmail.on.rhel.md
@@ -49,23 +49,17 @@ mx.example.com
 
 On RHEL/CentOS/Scientific Linux, hostname is set in two files:
 
-* For RHEL/CentOS/Scientific Linux 6, hostname is defined in `/etc/sysconfig/network`:
+1. `/etc/hostname`:
 
-```
-HOSTNAME=mx.example.com
-```
+    ```
+    mx.example.com
+    ```
 
-For RHEL/CentOS/Scientific Linux 7, hostname is defined in `/etc/hostname`.
+1. `/etc/hosts`: hostname <=> IP address mapping. Warning: List the FQDN hostname as first item.
 
-```
-mx.example.com
-```
-
-* `/etc/hosts`: hostname <=> IP address mapping. Warning: List the FQDN hostname as first item.
-
-```
-127.0.0.1   mx.example.com mx localhost localhost.localdomain
-```
+    ```
+    127.0.0.1   mx.example.com mx localhost localhost.localdomain
+    ```
 
 Verify the FQDN hostname. If it wasn't changed, please reboot server to make it work.
 
@@ -99,12 +93,14 @@ Disable it immediately without rebooting your server.
 
 ### Enable yum repositories for installing new packages
 
-* For CentOS or Scientific Linux, please
-    - enable CentOS/Scientific official yum repositories and `epel` repo.
+* On CentOS:
+    - Enable official yum repositories. On CentOS 8, please make sure repo
+      `AppStream` and `PowerTools` are enabled.
+    - Enable repo `epel`.
     - __DISABLE__ all other third-party yum repositories to avoid package conflict.
 
-* For Red Hat Enterprise Linux, please
-    - enable Red Hat Network to install packages, or create a local yum repository with DVD/CD ISO images.
+* On Red Hat Enterprise Linux:
+    - Enable Red Hat Network to install packages, or create a local yum repository with DVD/CD ISO images.
     - Enable `epel` repo (you can enable it by installing package `epel-release`)
 
 !!! attention
diff --git a/html/install.iredmail.on.rhel-zh_CN.html b/html/install.iredmail.on.rhel-zh_CN.html
index fa6f8e0f..b8d8e729 100644
--- a/html/install.iredmail.on.rhel-zh_CN.html
+++ b/html/install.iredmail.on.rhel-zh_CN.html
@@ -67,22 +67,16 @@ mx.example.com
 </code></pre>
 
 <p>在 RHEL/CentOS 系统上，主机名需要在两个文件里设置：</p>
-<ul>
-<li>对于 RHEL/CentOS 6，主机名定义在 <code>/etc/sysconfig/network</code>:</li>
-</ul>
-<pre><code>HOSTNAME=mx.example.com
-</code></pre>
-
-<p>对于 RHEL/CentOS 7，主机名定义在 <code>/etc/hostname</code>.</p>
-<pre><code>mx.example.com
-</code></pre>
-
-<ul>
-<li>在 <code>/etc/hosts</code> 里定义主机名和 IP 地址的对应关系。注意：一定要将 FQDN 主机名列在第一个。</li>
-</ul>
-<pre><code>127.0.0.1   mx.example.com mx localhost localhost.localdomain
-</code></pre>
-
+<ol>
+<li>
+<p>对于 RHEL/CentOS 7 和 8，主机名定义在 <code>/etc/hostname</code>.</p>
+<p><code>mx.example.com</code></p>
+</li>
+<li>
+<p>在 <code>/etc/hosts</code> 里定义主机名和 IP 地址的对应关系。注意：一定要将 FQDN 主机名列在第一个。</p>
+<p><code>127.0.0.1   mx.example.com mx localhost localhost.localdomain</code></p>
+</li>
+</ol>
 <p>确认系统已使用设置好的 FQDN 作为主机名。如果没有生效，请重启系统。</p>
 <pre><code>$ hostname -f
 mx.example.com
@@ -128,6 +122,12 @@ mx.example.com
 bash iRedMail.sh
 </code></pre>
 
+<p>如果是在 CentOS 8 系统上安装，iRedMail 安装程序会使用 <code>pip2</code> 命令安装几个
+Python-2 的模块，国内用户请指定镜像站点完成安装，否则很大可能会因网络问题
+导致安装失败：</p>
+<pre><code>PIP_MIRROR_SITE='http://pypi.douban.com/simple/' PIP_TRUSTED_HOST=pypi.douban.com bash iRedMail.sh
+</code></pre>
+
 <h2 id="_3">安装过程的截图</h2>
 <ul>
 <li>欢迎和感谢使用</li>
diff --git a/html/install.iredmail.on.rhel.html b/html/install.iredmail.on.rhel.html
index 8643cac0..d133926a 100644
--- a/html/install.iredmail.on.rhel.html
+++ b/html/install.iredmail.on.rhel.html
@@ -81,22 +81,16 @@ mx.example.com
 </code></pre>
 
 <p>On RHEL/CentOS/Scientific Linux, hostname is set in two files:</p>
-<ul>
-<li>For RHEL/CentOS/Scientific Linux 6, hostname is defined in <code>/etc/sysconfig/network</code>:</li>
-</ul>
-<pre><code>HOSTNAME=mx.example.com
-</code></pre>
-
-<p>For RHEL/CentOS/Scientific Linux 7, hostname is defined in <code>/etc/hostname</code>.</p>
-<pre><code>mx.example.com
-</code></pre>
-
-<ul>
-<li><code>/etc/hosts</code>: hostname &lt;=&gt; IP address mapping. Warning: List the FQDN hostname as first item.</li>
-</ul>
-<pre><code>127.0.0.1   mx.example.com mx localhost localhost.localdomain
-</code></pre>
-
+<ol>
+<li>
+<p><code>/etc/hostname</code>:</p>
+<p><code>mx.example.com</code></p>
+</li>
+<li>
+<p><code>/etc/hosts</code>: hostname &lt;=&gt; IP address mapping. Warning: List the FQDN hostname as first item.</p>
+<p><code>127.0.0.1   mx.example.com mx localhost localhost.localdomain</code></p>
+</li>
+</ol>
 <p>Verify the FQDN hostname. If it wasn't changed, please reboot server to make it work.</p>
 <pre><code>$ hostname -f
 mx.example.com
@@ -121,16 +115,18 @@ set below value instead:</p>
 <h3 id="enable-yum-repositories-for-installing-new-packages">Enable yum repositories for installing new packages</h3>
 <ul>
 <li>
-<p>For CentOS or Scientific Linux, please</p>
+<p>On CentOS:</p>
 <ul>
-<li>enable CentOS/Scientific official yum repositories and <code>epel</code> repo.</li>
+<li>Enable official yum repositories. On CentOS 8, please make sure repo
+  <code>AppStream</code> and <code>PowerTools</code> are enabled.</li>
+<li>Enable repo <code>epel</code>.</li>
 <li><strong>DISABLE</strong> all other third-party yum repositories to avoid package conflict.</li>
 </ul>
 </li>
 <li>
-<p>For Red Hat Enterprise Linux, please</p>
+<p>On Red Hat Enterprise Linux:</p>
 <ul>
-<li>enable Red Hat Network to install packages, or create a local yum repository with DVD/CD ISO images.</li>
+<li>Enable Red Hat Network to install packages, or create a local yum repository with DVD/CD ISO images.</li>
 <li>Enable <code>epel</code> repo (you can enable it by installing package <code>epel-release</code>)</li>
 </ul>
 </li>
diff --git a/zh_CN/installation/0-install.iredmail.on.rhel.md b/zh_CN/installation/0-install.iredmail.on.rhel.md
index 59fdf9d6..08ba98df 100644
--- a/zh_CN/installation/0-install.iredmail.on.rhel.md
+++ b/zh_CN/installation/0-install.iredmail.on.rhel.md
@@ -36,23 +36,17 @@ mx.example.com
 
 在 RHEL/CentOS 系统上，主机名需要在两个文件里设置：
 
-* 对于 RHEL/CentOS 6，主机名定义在 `/etc/sysconfig/network`:
+1. 对于 RHEL/CentOS 7 和 8，主机名定义在 `/etc/hostname`.
 
-```
-HOSTNAME=mx.example.com
-```
+    ```
+    mx.example.com
+    ```
 
-对于 RHEL/CentOS 7，主机名定义在 `/etc/hostname`.
+1. 在 `/etc/hosts` 里定义主机名和 IP 地址的对应关系。注意：一定要将 FQDN 主机名列在第一个。
 
-```
-mx.example.com
-```
-
-* 在 `/etc/hosts` 里定义主机名和 IP 地址的对应关系。注意：一定要将 FQDN 主机名列在第一个。
-
-```
-127.0.0.1   mx.example.com mx localhost localhost.localdomain
-```
+    ```
+    127.0.0.1   mx.example.com mx localhost localhost.localdomain
+    ```
 
 确认系统已使用设置好的 FQDN 作为主机名。如果没有生效，请重启系统。
 
@@ -109,6 +103,14 @@ cd /root/iRedMail-x.y.z/
 bash iRedMail.sh
 ```
 
+如果是在 CentOS 8 系统上安装，iRedMail 安装程序会使用 `pip2` 命令安装几个
+Python-2 的模块，国内用户请指定镜像站点完成安装，否则很大可能会因网络问题
+导致安装失败：
+
+```
+PIP_MIRROR_SITE='http://pypi.douban.com/simple/' PIP_TRUSTED_HOST=pypi.douban.com bash iRedMail.sh
+```
+
 ## 安装过程的截图
 
 * 欢迎和感谢使用