Reopen resolved ticket if/when end user replies

HI Please tell me how I can have a resolved ticket reopened if the end user replies via email after ticket is marked as resolved then a notification to assignee/agent sent to notify?

The default trigger which notifies assignees will work even if the ticket is closed. So the agent will be able to reopen the ticket when opened it:

But if you need to reopen the ticket automatically, you can add a custom trigger: