Rainloop

Install rainloop
 1) # wget https://www.rainloop.net/repository/webmail/rainloop-community-latest.zip
   or
    # https://www.rainloop.net/repository/webmail/rainloop-latest.zip   
 2) # unzip rainloop-community-latest.zip  -d /usr/share/rainloop
 3) # find /usr/share/rainloop -type d -exec chmod 755 {} \;
 4) # find /usr/share/rainloop -type f -exec chmod 644 {} \;
 5) # chown -R apache:apache /usr/share/rainloop
 6) # printf '%s\n' \
   '#' \
   '# Rainloop Webmail is a browser-based multilingual IMAP client' \
   '#' \
   'RewriteEngine On' \
   'RewriteCond %{HTTPS} off' \
   'RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}' \
   'Alias /rlmail /usr/share/rainloop' \
   '<Directory /usr/share/rainloop/>' \
   '    Options +Indexes +FollowSymLinks +ExecCGI' \
   '    AllowOverride All' \
   '    Require all granted' \
   '    ErrorLog "/var/log/httpd/rainloop_error_log"' \
   '    TransferLog "/var/log/httpd/rainloop_access_log"' \
   '</Directory>' \
   '<Directory /usr/share/rainloop/data/>' \
   '    Require all denied' \
   '</Directory>' \
   > /etc/httpd/conf.d/rainloop.conf

 7) # yum -y install php-xml
 8) # systemctl restart httpd

Configure (username: admin, password: 12345)
 9) https://yourserver/rlmail/?admin/
10) Add your domain, IMAP server, SMTP server, ...Do not use short login
11) Add contact support if needed. Requires DB support.

# Login to email account
12) https://yourserver/rlmail 
13) Additional Tutorial
14) 2-Factor Authentication