SquirrelMail Webmail Installation on CentOS

Provides a tutorial example on how to install SquirrelMail on CentOS computers as a Web-based email client tool.

What Is SquirrelMail? SquirrelMail is a free open source Web-based email client tool for Linux systems that integrates to Postfix and Dovecot local servers. It includes built-in pure PHP support for IMAP and SMTP, and renders all pages in pure HTML 4.0 for maximum compatibility across browsers. It has strong MIME support and a flexible plugin system.

The latest stable version is SquirrelMail 1.4.22, which seems to be outdated (released in 2011). So I decided to try the "stable version snapshot" version, SquirrelMail 1.4.23-svn, released in 2020.

1. Go to SquirrelMail Website at http://squirrelmail.org.

2. Click "Download" from the left menu. You see the download page.

3. Click "squirrelmail-20201119_0200-SVN.stable.tar.gz" to download it.

4. Unzip and un-tar the download file. You see the ./squirrelmail.stable/squirrelmail sub-directory.

5. Install SquirrelMail on the web server. Remember to backup the old Webmail HTML directory, if exists.

herong$ sudo mv /var/www/html/mail /var/www/html/mail-old

herong$ sudo mv ./squirrelmail.stable/squirrelmail /var/www/html/mail

6. Fix ownership and security context.

herong$ cd /var/www/html

herong$ sudo chown -R root mail
herong$ sudo chgrp -R root mail
herong$ sudo chcon -R -t httpd_sys_content_t mail

7. Test installation by open in a Web browser. You see SquirrelMail documentations. Read the "INSTALL - Installation instructions" page.

SquirrelMail Webmail - Web-Based Email Client
SquirrelMail Webmail - Web-Based Email Client

Table of Contents

 About This Book

 Introduction to Linux Systems

 Cockpit - Web Portal for Administrator

 Process Management

 Files and Directories

 Users and Groups

 File Systems

 Installing CentOS

 SELinux - Security-Enhanced Linux

 Network Connection on CentOS

 Software Package Manager on CentOS - DNF and YUM

 Running Apache Web Server (httpd) on Linux Systems

 Running PHP Scripts on Linux Systems

 Running MySQL Database Server on Linux Systems

 Running Python Scripts on Linux Systems

 vsftpd - Very Secure FTP Daemon

 Postfix - Mail Transport Agent (MTA)

 Dovecot - IMAP and POP3 Server

Email Client Tools - Mail User Agents (MUA)

 "mailx" Command - Send and Read Emails

 "Alpine" - Terminal-Based Email Client

SquirrelMail Webmail Installation on CentOS

 SquirrelMail Configuration on CentOS

 Thunderbird Installation on macOS

 Thunderbird Configuration for POP3S and SMTP

 Thunderbird to Accept POP3S Certificate Exception

 Thunderbird Configuratin for SMTPS Service

 macOS Mail Auto Configuration

 macOS Mail Manual Configuration

 Accept Certificate Exception in macOS Mail

 Windows 10 Mail Configuration Failed

 SSL/TLS Connection Issue in Windows 10 Mail

 GCC - C/C++ Compiler

 Conda - Environment and Package Manager

 Tools and Utilities


 Full Version in PDF/EPUB