When using MailMerge from Word using HTML, the email does not send or user experiences word freezing problem.
This is a product defect caused due to a conflict when Print Monitoring channel is ON.
DLP Endpoint Release : 15.8 MP1
The issue has been fixed in Public Hotfix 15.8.00109.01003 released on Nov 03, 2021 which can be downloaded from the Broadcom support portal (https://support.Broadcom.com/Downloads)