If you press the "Connect to Outlook" button on the ribbon of a calendar in SharePoint 2010 the server creates a URL similar to the following: stssync://sts/?ver=1.1&type=calendar&cmd=add-folder&base-url=http%3A%2F%2FSITEURL&list-url=%2FLists%2FTeam%2520Calendar%2F&guid=%7Ba0b6a3dc%2D8416%2D48bf%2D9fa1%2D1f2c45fb3fb3%7D&site-name=SITENAME&list-name=Team%20Calendar. If you go to Outlook you may see a Send-Receive error stating: Task ‘SharePoint’ reported error (0x800004005) : This SharePoint List (xxxxxxxx Site - Team Calendar) is blocked from download to offline clients.’ . There are two possible reasons for this error.
- Under Site Settings - Site Administration - Search and Offline Availability - Offline Client Availability check that yes is selected.
- Under List Settings - Advanced Settings - Offline Client Availability check that yes is selected.
SharePoint 2010 gives you the ability to disallow offline client availability on both site and list level.