When emails come into CT Suite, the system has a way of knowing if the email is a parent or a child. Understanding this parent/child relationship is key to searching and displaying emails in a thread, and can also be useful when developing workflows and agent processes.
Definitions:
Parent email - a brand new email with no related email in the system.
Child email - an email that is part of an existing thread, or conversation. Child emails are created by replying, forwarding or creating a new child email from the parent email.
How it works
CT Suite uses a unique email identifier for each parent email. This identifier is placed in the footer of every incoming or outgoing parent email. This "Parent ID" is not visible in the CT Suite email viewer, but other email applications may display it.

The Parent ID of an email corresponds with the Email ID from the original parent email. Subsequent child emails will all have their own unique Email ID, but they will contain the Parent ID in the email footer. This is so you can search for the whole email thread by searching the Parent ID as a keyword.