roundcube is running on the same server as my postfix and dovecot services ie IMAP and SMTP so there all on localhost
what i did to install roundcube, i downloaded/extracted the tar file using 7.zip, i then copied the contents of the roundcube folder to my /var/www/html/roundcube via filezilla an ftp client so i SSH'd in on the server to copy the folder over
next step is because the server is centos 6.6, i needed to upgrade it to php 5.4.42 from php 5.3.3
bear in mind once you have upgraded php to install the dependencies its like this
php54w-ldap php54w-mbstring php54w-mysql instead of just php-ldap php-mbstring php-mysql
next step i opened up a web browser and typed in ip_address_of_server/roundcube/installer and went through the steps in configuring roundcube via the web gui and job done
to fix the error so no users can access the installer i added this line
$rcmail_config['enable_installer'] = false;
also i added this line as when i was sending from roundcube the from field was marked up as user@localhost instead of
user@domain.co.uk
$config['mail_domain'] = 'domain.co.uk';
or instead of adding the line above in yoour roundcube config file you can do this
go into "/etc/hosts" and add my email public DNS to it ie"robina.ddns.net"