This code showed me the different TypeNames that were in my Inbox:
Public Sub GetTypeNamesInbox()
Dim myOlItems As Outlook.Items
Set myOlItems = application.GetNamespace("MAPI").GetDefaultFolder(olFolderInbox).Items
Dim msg As Object
For Each msg In myOlItems
Debug.Print TypeName(msg)
'emails are typename MailItem
'Meeting responses are typename MeetingItem
'Delivery receipts are typename ReportItem
Next msg
End Sub
HTH