To include the unassigned email in a customer timeline you will need to assign the email to that specific customer.
Task manager ➡️ Tasks ➡️ Unassigned customer communications ➡️ Select Email ➡️ Type in Customer ➡️ Click Assign
Detailed guide:
To assign your emails go into your task manager
Select your tasks tab – you should see the unassigned communications in its own separate tab.
Click on view & assign
This will bring up the list of all unassigned emails
Select an email this will open up the email in preview – there is a bar on the top where you can type in the customer name & click assign