the problem seems to be when converting the message from SMTP to Notes format. This usually is done on the server side, not on the client side. So at least for our complany, we dont care about the Notes Client. Of course we 're upgrading servers to 7.0.3
If the conversion is done on the server or on the client depends on how the system is configured. If the setting in the person doc says Keep in senders format, then the conversion is done on the client, so it is vulnerable and you should definately upgrade to 7.0.3.