Custom form and encrypted message

[Asa H]

I have created a custom form and made it the default for all e-mail
messages with the formswap utility. When I receive an encrypted and
signed message my custom form is not used. Instead the message is
opened with the Outlook standard IPM.Note form. Why? What can I do
about this?

The custom form is used with Outlook 2000 and 2002.

Thanks in advance
Asa