I have been tasked with setting up a helpdesk system recently and settled on two systems to try, OSTicket being one. The problem was neither of them seemed to deal with Google apps very well. Every time I tested a system out with Google/a I either got a timeout error or simply just a overall failure. I used all the forum tricks, triple checked my settings, I was stumped. I damn near rewrote the pop3.php file for another helpdesk system trying ot get it right.
It took me a few hours before it dawned on me that I have a firewall on our dedicated server.
If you are having issues with remote piping, pop3 or IMAP retrieval and it is causing your help desk to not function, double check to make sure you have the proper ports opened up.
I use the most excellent http://www.configserver.com(http://www.configserver.com) which is free. If you are using this as well, simply go to the "Firewall configuration" button, do a find for TCP_OUT, and make sure 995 is added, (in the case of Google apps mail).
This caused me all sorts of strife, but all is well now. :)
Yes, I realize I am calling myself stupid on the internet for forgetting about my firewall, but hopefully this will help somebody else out.