When clicking "Release" in the Symantec Data Loss Prevention (DLP) Enforce Server console to release a message stored in the Symantec Messaging Gateway (SMG) Content Quarantine Incident folder, you see the error:

FlexResponse Action Failed
[Email Quarantine Connect Approve Action] failed with message:
javax.net.ssl.SSLHandshakeException; Received Fatal alert: certificate_unknown

You are using the Endpoint FlexResponse plug-in.

The certificate issued on the DLP Enforce Server and imported in SMG may be invalid. This certificate is used for encrypted communication between the DLP Enforce Server and the SMG Control Center.

Delete the new certificate imported on SMG, and generate a new one from the DLP Enforce Server. The new certificate should contain the correct information of the DLP Enforce Server, which needs to be recognized by SMG.

See Symantec DLP 15.7 Email Quarantine Connect FlexResponse Implementation Guide.

See Symantec DLP 15.8 Email Quarantine Connect FlexResponse Implementation Guide.

Once reissued, import the new certificate in SMG. See Importing an application certificate.