Outlook.Application.CreateItem can return different types depending on the given argument.
Now it returns die COM object directly. It could return directly the COM object wrapped in the correct class.
# Now
# return instance must be wrapped in `MailItem` class
mail = ol.MailItem(ol_app.create_item(ol.olMailItem))
# After
# return `matita.outlook.MailItem` instance directly
mail = ol_app.create_item(ol.olMailItem)