Can't find any description of Justpak, but justhost does have a knowledgebase that makes for interesting reading.
For one, I saw a recommendation that customers change their STMP port to 26. PHPMyAdmin limited to 50M imports ... larger than that, one has to use command line. Ahhhh, if you are willing to work from command line, ssh is available (but you have to request setup and verify etc.). The operating system is CentOS 6.4. If you haven't run into PHP scripts needing more memory, longer running time, etc., check the following link out as you will have to do PHP settings this way:
The only specific reference they have for Moodle is related to the location of the config.php file.
From what I can find, looks like they use Exim as their MTA:
In many years of administering internet servers (of all three flavors) I eventually decided the real power is on the command line. It's a learning curve, but we do what we must (and it's not all that bad, especially when one can see results almost immediately).
justhost even has a little help:
All in all, I'd say one has to learn what the hosting provider is providing and how to do xyz using their system!
'spirit of sharing', Ken