How to Install SquirrelMail on CentOS 7

Squirrelmail is one of the most popular Web-based email clients written in PHP. It has built-in pure PHP support for IMAP and SMTP, and it is designed to render all pages in pure HTML 4.0 with no JavaScript required, for maximum compatibility across browsers. Its installation and configuration is pretty simple. Note that if you have a VPS with WHM/cPanel or DirectAdmin, Squirrelmail comes preinstalled and ready to use with these control panels.