I'm trying to get Horde to display inline HTML but for some reason the info I'm finding online is just not working.

I've found instructions from horde to do this:

$mime_drivers['imp']['html']['inline'] = true; // for horde/config/mime_drivers.local.php

$mime_drivers['html']['inline'] = true; // for horde/imp/config/mime_drivers.local.php

I've changed every mime_drivers.local.php AND mime_drivers.php that I can find on the server and it just doesn't work. Am I missing something? Is there something I need to restart to get this to work? I've read where others state they never had to restart any services, it just started working. I've messed with this for far too many hours already.

I'll also mention Horde is enabled through Plesk if that makes any difference.

Any help would be greatly appreciated.