The IMAPIViewAdviseSink::OnNewMessage method notifies the form viewer that either a new or an existing message has been loaded in a form.
See IMAPIViewAdviseSink : IUnknown.
HRESULT OnNewMessage();
None
Form objects call the IMAPIViewAdviseSink::OnNewMessage method whenever a message is loaded in a form using either the IPersistMessage::InitNew or IPersistMessage::Load method.
Release your active pointer to the form object because it no longer points to the message your viewer was formerly viewing.
For more information about form notifications, see Sending and Receiving Form Notifications.
IMAPIForm : IUnknown, IPersistMessage::InitNew, IPersistMessage::Load