The right text must be:
Change the line $rcmail_config['virtuser_file'] = '';
$rcmail_config['virtuser_file'] = '/etc/postfix/virtusertable';
But we found out here: http://www.howtoforge.com/forums/sho...ight=roundcube
that if we do so, the identitiy settings will not be saved in case you login with email@example.com
So my advise for this moment is leave the line:
$rcmail_config['virtuser_file'] = '';
$rcmail_config['smtp_server'] = '';
chown -R www-data:www-data temp
chown -R www-data:www-data logs
You set the Apache permissions, so it can write to the directories temp & log, which is necesarry.
I hope this information is helpful to you to setup RoundCube successfully!
The howto will be updated today.