When I attempted to send a PKI-encrypted email message to several recipients from Microsoft Outlook for Mac 2016 (version 15.41), I saw the message "Encryption certificates for some recipients could not be found in the Outlook Contacts. Do you want to search the Active Directory servers for them?"
I clicked on OK and then saw the message "The following recipients have encryption certificates with security problems. Do you still want to send this encrypted message?"
I clicked on Cancel and checked on whether Outlook was storing a public key certificate for the person in my contacts list. He was in the contact list, but there was no certificate associated with the person in the contacts list when I clicked on the Certificates tab.
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