Lotus Script and Digital Certificate

Hello ,I had configured the certficate authority on the Domino Server to have my own CA to issue certficates.

I try to develop an application that recieves signed mails from Notes users and MS Excahange users.

The application supposed to process all the incoming mails.

I want to know how to check the signature of the messages using lotus script, and to check that the messages was signed by the certificate issued to the user from my domino CA for both Notes and Exchange users.

Thanks in advance.