You will need to search for the MessageClass property (PR_MESSAGE_CLASS in
Extended MAPI) being "IPM.Note.SMIME.MultipartSigned" or "IPM.Note.SMIME".

Dmitry Streblechenko (MVP)
http://www.dimastr.com/
OutlookSpy - Outlook, CDO
and MAPI Developer Tool

wrote in message
oups.com...
I'm searching for a way to detect if the mail is signed/encrypted.

The only idea i have is to search for multipart/signed and
multipart/encrypted content type, but MAPI doesn't seem to implement
content-type.