I've been watching this question:
In comparing it with the document that was sent to one of our admins (see attached), I'm noticing some discrepancies. The document implies that you need two separate emails - one for ticket creation, and one for replies - but the question says you can use one mailbox. Granted, the document is old, but I just wanted to make sure.
We are currently using one email for ticket creation, and one for ticket replies, but the address for ticket replies sometimes gets cached in our clients' Outlook profiles, so I discovered last week that they will sometimes email our replies address and never get a response because we don't check it regularly. We are working on changing the display name of our email address and removing it from our GAL, but I am also thinking that one mailbox would be the way to go, if that's possible.