Gets the most recent download time for all feed items.
HRESULT IFeed2::get_LastItemDownloadTime(DATE *lastItemDownloadTime);
Pointer to a variable of type DATE that receives the date and time of the item most recently downloaded.
Returns S_OK if successful, or an error value otherwise.
The retrieved time is adjusted for the local time zone.
If there are no items in the feed, the retrieved value is 0, which represents the date and time
"Sat Dec 30 00:00:00 PST 1899".