Does anyone know of a way how to figure out which public key (certificate) Outlook used to encrypt mail for a certain recipient?
The idea is that we are using AD-integrated Certificates and one user has 4 published certificates linked to his AD object. Now another user from our organization (Outlook/Active Directory/Exchange on-prem), just sent an email with S/MIME via Outlook to this recipient. And we'd like to figure out which certificate (from the 4) his Outlook used to encrypt the mail? Because if any other user sends an encrypted message to this recipient, the certificate with longest validity is used and the recipient can open this mail just fine. This he cannot do for the email of my first sender.
kind regards,
Dieter

