The DeleteMessages method deletes one or more messages from the current folder.
HRESULT DeleteMessages ( LPENTRYLIST lpMsgList, ULONG ulUIParam, LPMAPIPROGRESS lpProgress, ULONG ulFlags );
This method returns the standard values E_INVALIDARG, E_OUTOFMEMORY, E_UNEXPECTED, and E_FAIL, as well as the following:
The call succeeded, but not all of the messages were successfully deleted. When this warning is returned, the call should be handled as successful.
Messages that do not exist, that have been moved elsewhere, that are open with read/write access, or that are currently submitted cannot be deleted.
When DeleteMessages is unable to complete, do not assume that no work was done. DeleteMessages might have been able to delete one or more of the messages before encountering the error.