Trigger a Message using Sophos Endpoint

Hi blueskies ,

Thank you for reaching out to the Sophos Community Forum.

Could you explain this further, please? Would you like to trigger an Endpoint alert? Kindly provide more context. Thank you.

Ok , SCENARIO 500 VMs which includes clients and Servers. These are basically from certain labs as these VMs were created for testing purpose and left active.  Sophos is on these VMs which are spread globally in different regions on many VCenters. Due to some Core agent conflict with a KB missing from windows now Sophos is popping ACS Azure error. Solution is to install the KB on these systems but after PROPER TEST and BACKUP. Since these are randomly created test VMs but are required to be retained. These VMs are not on Asset Inventory nor on our Software management system for patch deployment or tracing. Security wise they are well zoned in a certain network. 
Also Login IDs to these VMs are auto generated and cant be associated to a user.

Thus easiest would be for me to pop up a message on the endpoint to contact XYZ person for certain update citing Urgent.

As far as I know, there's no custom messaging capability within Intercept X. You'd be better off using native Microsoft functionality for the message, based on a list of the relevant computers from Sophos Central.