Problem

Mailgate SC Add-in for Outlook is unable to render new secure messages after installing the October 2017 Microsoft Outlook security update (KB4011196)

New items are displayed as "opened envelope" with no sender/recipient/subject/body. The older and read messages are not showing in the SC folders at all.

Resolution

Microsoft has forbidden the roaming home pages as part of this security update, and that seems to affect many Outlook addins, including Mailgate SC Add-in: https://social.technet.microsoft.com/Forums/en-US/...

Microsoft suggests that the security update must remain installed but in order to re-enable roaming home pages as a workaround while a permanent resolution is developed, a registry key must be added to the local client machines running the Outlook application.

The workaround proposed by Microsoft is available here: https://support.microsoft.com/en-us/help/4049314/m...

NOTE: This update affects different Outlook versions, which means it could affected older MG SC Add-in versions too.