I've done a search of the forums and see a number of posts about this topic, but only one response from X1: and that response says, "Yes, you need to manually exit X1 to close your PST files and release your Exchange connection."
I run Outlook all day long. The only time I exit Outlook is when I plan to reboot or run a backup. I don't always remember to exit X1, and when I don't remember to exit X1 my backup fails; which leaves me needlessly exposed (since I don't have time in the morning to re-run the backup when it fails).
Please add an option to the X1 configuration that causes X1 to fully close when Outlook is closed.