Author: Mike Shkolnik

Do you want to use the MS Outlook from Delphi application?

Answer:

The procedure below allow to load a tree of available folders into TTreeView: 

1   procedure RetrieveOutlookFolders(tvFolders: TTreeView);
2   
3     procedure LoadFolder(ParentNode: TTreeNode; Folder: OleVariant);
4     var
5       i: Integer;
6       node: TTreeNode;
7     begin
8       for i := 1 to Folder.Count do
9       begin
10        node := tvFolders.Items.AddChild(ParentNode,
11          Folder.Item[i].Name;
12  
13          LoadFolder(node, Folder.Item[i].Folders);
14      end;
15    end;
16  
17  var
18    outlook, NameSpace: OLEVariant;
19  begin
20    outlook := CreateOleObject('Outlook.Application');
21    NameSpace := outlook.GetNameSpace('MAPI');
22  
23    LoadFolder(nil, NameSpace.Folders);
24  
25    outlook := UnAssigned;
26  end;


A few comments: 

the data in Outlook have the next structure: outlook application defines a MAPI's 
namespace which have a collection of folders. Each folder contains an items or 
sub-folders 
this code load a full tree in TreeView. Of course, if you have a lot of pst-files 
with messages (active, archive, backup etc) and each of this pst-file have a large 
structure of folders, this code will work slowly. So as suggestion: you can rewrite 
a code and load the one level only. In this case code will work quickly and a list 
of sub-folders you'll receive in OnExpanding event of your TreeView 
each folder of Outlook have an unique idenifier. You can save it somewhere (for 
example, in Data property of TTreeNode). Remember that this ID is long string value 
which you can receive as EntryID in loop of LoadFolder procedure: 

Folder.Item[i].EntryID

PS: if this topic is interested for you, I'll continue this serie of tips and shall show how to load the messages/contacts/tasks/etc from some folder or create a new item.