|EwsDownloadItemIds Method (FolderId, ItemView, Boolean)|
public EwsItemList DownloadItemIds( FolderId id, ItemView view, bool unreadOnly )
Public Function DownloadItemIds ( id As FolderId, view As ItemView, unreadOnly As Boolean ) As EwsItemList
Usually, you'll immediately pass the returned list to a method like DownloadItems(IEnumerableEwsItem, EwsItemParts). However, once you downloaded the item IDs, you can also store UniqueId values elsewhere and later recreate EwsItem objects from that strings using EwsItem(String) constructor.
Items are returned in the default sorting order which usually means "newer first" in Exchange. This is different from IMAP and POP3, where "older first" is the default.