VSTO plug-in: Digital ID name cannot be found by the underlying security system.

Question

I have developed an outlook plug-in. I have deployed this with outlook 2016 and for particular user, we are getting following exception while accessing different fields like subject, attachment or sender information :--

our Digital ID name cannot be found by the underlying security system.
at Microsoft.Office.Interop.Outlook._MailItem.get_SenderEmailType()

Your Digital ID name cannot be found by the underlying security system.
at Microsoft.Office.Interop.Outlook._MailItem.get_Attachments()

Can somebody suggest why these exception comes and what is solution ? Initially I thought it is because user had old s/mime encrypted mails. But we are getting this exception in draft also for newly created draft mails as well.

Thanks
Dev

Answer 1

Actually I found reason partially. It is happening because s/mime certificate was not configured on that user machine. I can understand the impact of it in s/mime mails.

But I still dont understand, for draft, even we have not switched on s/mime, why it is throwing exception.
Does it mean that if s/mime is configured, irrespective of all options are disabled from trust centre and encrypt and sign has not selected, still, s/mim perform encryption on draft mail in outlook ?

Anu thoughts ?

Thanks
Dev