I use the following VBA code snippet in other Office Applications, where the Outlook Library is directly referenced.
' Outlook Variables
Dim objOutlook As Outlook.Application: Set objOutlook = New Outlook.Application
Dim objNameSpace As Outlook.NameSpace: Set objNameSpace = objOutlook.GetNamespace("MAPI")
Dim objFolder As MAPIFolder: Set objFolder = objNameSpace.PickFolder()
Dim objMailItem As Outlook.MailItem
Dim iCounter As Integer: iCounter = objFolder.Items.Count
Dim i As Integer
For i = iCounter To 1 Step -1
If TypeOf objFolder.Items(i) Is MailItem Then
Set objMailItem = objFolder.Items(i)
With objMailItem
etc.