What happened
A Microsoft Classic Outlook bug prevents opening encrypted emails in Outlook 2016 and 2019 due to improper handling of S/MIME certificates. Users attempting to open encrypted or signed emails encounter errors, affecting business communication and confidentiality.
Who is affected
Enterprises and individuals using classic Outlook versions with S/MIME encryption face direct exposure, potentially hindering secure email delivery.
Why CISOs should care
Inability to access encrypted email can disrupt business workflows, compliance, and secure communications.
3 practical actions
Update Outlook clients: Apply patches or use supported versions.
Verify S/MIME certificate validity: Ensure certificates are current and correctly installed.
Provide alternative secure channels: Implement temporary encrypted communication methods until fixed.