First of all, the "magic" thing needed there is only a file. So it should be sufficient to copy the file magic from /usr/share/file/magic to a dir inside open_basedir and then edit the config file to point $rcmail_config['mime_magic'] directly to this file (path and filename).
Furthermore the config and the error message you are receiving do not make sense.
If the variable is configured to '/var/www/vhosts/demo1234.org/httpdocs/roundcube/magic/magic' why does it search the file in here: '/usr/share/roundcube/magic/magic'.
the reason the config and the error didn't match is because I have been moving and changing it so many times I gave the wrong log entry for the wrong time.
The error msg was correct, the path was not.
I still get the error no matter if I point to the file, or just the path that contains the file. I am still not sure which is correct.
I have checked the permissions and it is owned by the same group/user as the rest of the roundcube installation and just to be sure, I changed the permissions to 666 even though we know it should never be writing there..
Still the error. This is on a CentOS 5.6 machine. and the PHP is 5.3.6
One thing I noticed in the php.net documentation for the finfo_open is that if the file is NULL then it uses the system default. I set my path to NULL and no more errors.. So, I don't know if that means it is working now, or not even trying to read it.
How can I test this to see if it is being read properly?