Yes, it will break Zarafa with the following message:
Not Found: PHP mapi extension not found
If you have upgraded zarafa, please restart Apache
Zarafa WebApp can't start because of incompatible configuration.
Please correct above errors, a good start is by checking your '/etc/php.ini' file.
Or if you wish, you can disable this config check by editing the file '/usr/share/zarafa-webapp/config.php', but this is not recommend.
In my quick tests, it works fine for Joomla!, WordPress and Tiki Wiki CMS Groupware. I didn't try ownCloud but I suspect it works fine as well.
So I am wondering if there are any recipes out there to set up a minimal ClearOS instance on a rented server, whose sole purpose is to tunnel info to my local ClearOS. This adds a point of failure, but it's an acceptable compromise in this case. No information would live on the server, so I wouldn't even set up backups for data.
I think Nathan needs to clarify how his system is setup. It sounds like he's using ClearOS as a gateway server and that he is or was running a PLEX server on a Windows7 PC behind ClearOS. It sounds like he wants to only use ClearOS as a gateway appliance. What say ye Nathan?