protect content of custom message class when Outlook cannot open the custom MAPI form

[movalgirl]

Hi all,

I have a custom message class with an associated Custom MAPI form. On
occasion, the Custom MAPI form cannot be opened and the user gets the
message.

“The custom form cannot be opened. Outlook will use an Outlook form
instead. The form required to view this message cannot be displayed.
Contact your administrator"

Can I prevent the Outlook form from modifying the contents of the
message? In other words. Is there a way to tell
the Outlook form that this message is ReadOnly?

Thanks,
movalgirl