Sub ListMailsInFolder()

    Dim objNS As Outlook.NameSpace
    Dim objFolder As Outlook.MAPIFolder

    Set objNS = GetNamespace("MAPI")
    Set objFolder = objNS.Folders.GetFirst ' folders of your current account
    Set objFolder = objFolder.Folders("Foldername").Folders("Subfoldername")

    For Each Item In objFolder.Items
        If TypeName(Item) = "MailItem" Then
            ' ... do stuff here ...
            Debug.Print Item.ConversationTopic
        End If
    Next

End Sub