I have some EML files that I’m loading into MailMessages, and need to exclude items that are signed or encrypted. When opening with Outlook they are clearly signed, but MailMessage.CheckSignature and IsSigned both show the items as not signed. The item class is just IPM.Note and header content type is Tnef so I can’t check regular MIME header properties. Is there a way to reference other internal fields to determine this after Aspose has decoded the Tnef content?
After having a quick navigation through our product documentation, I have found that currently Aspose.Email does not have an exact method for defining whether a message is encrypted.
Similarly IsSigned shows ‘true’ only for the following content-type values:
“application/pkcs7-mime”, “application/x-pkcs7-mime”, “multipart/signed”.
Please spare us little time as we are investigating the issue and discussing it with the developers. We will share our findings soon via this forum.
You may please have a look at Link for further detail about S/MIME.