A recent technote on the IBM support website was published that more clearly explains a new default value that may catch you by surprise.  It allows Traveler to access the mail file as the user rather than as the Traveler server.  This can be impacted by security settings in the server documents of the mail server and the Traveler server.  So if users are having issues with synchronizing their mail after the upgrade, this is a good article to start with for troubleshooting.