Be advised that in addition to earlier reports, there are not only data loss issues with Exchange 2010 SP1 Rollup 4 when moving folder structures from public folders to mailboxes or other public folders.  Apparantly, data loss can also occur when moving folder structures to PST files. In both cases, only the top folder and messages are moved, subfolders and their contents are not moved but deleted.

On the issue, Microsoft’s Ross Smith said the following:

In SP1 RU4 we addressed the issue where you could not recover deleted public folders from dumpster. However, Outlook incorrectly passes a flag that indicates the item has been deleted when it has not.  As a result, when you perform a copy or move in the manner Jens described, the sub-folders are deleted.  As mentioned previously, you can recover these deleted folders from dumpster.  We’ve contacted the Outlook team to assist in further diagnosis of the issue and to help us determine the right vehicle for a fix, we’ll provide more details soon – in the meantime please open a CSS case.

You can uninstall Rollup 4 from your Exchange servers to prevent potential data loss caused by these issues.

Note that Rollup 5 is scheduled for August, so you might start to wonder what will arrive first, RU5 or RU4v2.