尝试使用 yum 在 CentOS 7 上安装 PostFIX 时：
yum install postfix
它提供了以下反馈并且未安装：
Loaded plugins: fastestmirror, universal-hooks
Loading mirror speeds from cached hostfile
* EA4: 169.255.59.74
* cpanel-addons-production-feed: 169.255.59.74
* base: repos-jnb.psychz.net
* epel: mirror.wbs.co.za
* extras: repos-jnb.psychz.net
* nux-dextop: mirror.li.nux.ro
* updates: repos-jnb.psychz.net
Resolving Dependencies
--> Running transaction check
---> Package postfix.x86_64 2:2.10.1-6.el7 will be installed
Removing postfix.x86_64 2:2.10.1-6.el7 - u due to obsoletes from installed exim-4.89-2.cp1162.x86_64
--> Restarting Dependency Resolution with new changes.
--> Running transaction check
---> Package postfix.x86_64 2:2.10.1-6.el7 will be installed
--> Finished Dependency Resolution
我甚至尝试通过 Cpanel WHM 安装外部 SSH，它给出的反馈如下：
Loaded plugins: fastestmirror, universal-hooks
Loading mirror speeds from cached hostfile
* EA4: 169.255.59.74
* cpanel-addons-production-feed: 169.255.59.74
* base: repos-jnb.psychz.net
* extras: repos-jnb.psychz.net
* nux-dextop: mirror.li.nux.ro
* updates: repos-jnb.psychz.net
Resolving Dependencies
--> Running transaction check
Removing postfix.x86_64 2:2.10.1-6.el7 - u due to obsoletes from installed exim-4.89-2.cp1162.x86_64
--> Restarting Dependency Resolution with new changes.
--> Finished Dependency Resolution
Install complete.
我对 Linux 和 CentOS 还很陌生，似乎无法弄清楚问题出在哪里。我采取的措施：
重建 RPM 数据库
yum remove postfix
yum reinstall postfix
任何建议将不胜感激。
答案1
顺便问一下，你跑步了吗yum update？
尝试添加/etc/yum.conf：
obsoletes=0
或者exim先安装包：
yum --setopt=obsoletes=0 install postfix