In IDM environment IM process generates the “Task ID” while IP process generates the “Request ID”.
Customers normally want to send “Request ID” generated by IP in email for reference.
In IP you can retrieve the generated “Request ID” from “Server Type->Hidden-> Request ID” attribute. You need to store this “Request ID” in some SLA attribute ( corresponding to IM task) and after that access this SLA in email policy to embed “Request ID” into the email body.
Reference: https://techdocs.broadcom.com/us/en/symantec-security-software/identity-security/identity-portal/14-4/administrating/identity-portal-administration/elements/backend/create-forms.html