The code I use requires CDO, which may not be available since it's an
optional installation for Outlook 2000 and later. First I get the Outlook
version (Application.Version) as a string and look at the 2 left characters
of the string. If the leftmost one is "9" it's Outlook 2000, if "10" it's
Outlook 2002 and if "11" it's Outlook 2003. Then I call the following
procedure.

' olConnectMode is a global defined as follows:
Public Enum OL2003ConnectionMode
 CacheConnectDrizzle = 600
 CacheConnectFull = 700
 CacheConnectHeaders = 500
 CacheDisconnect = 400
 CacheOffline = 200
 Disconnect = 300
 NoExchange = 0
 Offline = 100
 Online = 800
End Enum

Public olConnectMode As OL2003ConnectionMode

Private Function UserOnline() As Boolean
 On Error Resume Next

 Const PR_STORE_OFFLINE = &H6632000B
 Const CdoPR_PROVIDER_DISPLAY = &H3006001E

 UserOnline = False
 olConnectMode = Online

 With g_objDefaultInfoStore 'gotten by using Inbox.StoreID and
Session.GetInfoStore
   If g_lngVersion >= 10 Then 'g_lngVersion set as Outlook version as a
Long
     UserOnline = Not (g_objApp.Session.Offline) 'not available for Outlook
2000
     If g_lngVersion = 10 Then
       If Not UserOnline Then
         olConnectMode = Offline
       End If
     ElseIf g_lngVersion = 11 Then
       olConnectMode = g_objApp.Session.ExchangeConnectionMode

       If InStr(1, .Fields(CdoPR_PROVIDER_DISPLAY), _
         "Microsoft Exchange", vbTextCompare) > 0 Then

         If ((UserOnline) And (olConnectMode = NoExchange)) Then
           olConnectMode = Offline
         End If
       End If
     End If
   Else
     If InStr(1, .Fields(CdoPR_PROVIDER_DISPLAY), "Microsoft Exchange", _
       vbTextCompare) > 0 Then

       'Check if store is in offline mode
       UserOnline = Not (.Fields(PR_STORE_OFFLINE).Value)

     ElseIf InStr(1, .Fields(CdoPR_PROVIDER_DISPLAY), "Personal Folders", _
       vbTextCompare) > 0 Then

       UserOnline = True
     End If

     If Not UserOnline Then
       olConnectMode = Offline
     End If
   End If
 End With

 If Err <> 0 Then
   LogAddInErr Err, "clsAddin", "UserOnline", "Error!"
   'Err.Clear
 End If
End Function