When using an AI Agent and the conversation goes inactive, how do I update the template that is used for that email?

I've searched everywhere and cannot find this. 

I know how to update the email template for the Email channel. 

I am looking for the email template that is used when a Messaging conversation changes to Inactive. 

I want to change the subject line.  Also, I want to add some text like “You can reply via email or via the message bubble.” 

I can'f figure out how to do this under Messaging Triggers. 

When I check under the regular Triggers, I don't see a placeholder to add in the conversation to the Notify Via Email action. 

Here is the email I am referring to: