I don't receive email updates when a customer responds to a ticket

Issue symptoms

I'm not getting email updates when a user has a follow-up email. I only get notifications about the first email from my customers. I do not get notified about follow-up emails in the thread. 

Resolution steps

The Notify assignee of comment update default trigger is commonly used to notify the agent assigned to the ticket of any ticket update. If you edit this default trigger, or add another trigger of similar functionality, notifications may not send as expected. 

To resolve the issue: 

1. Identify the trigger on an example ticket that did not send a notification to the assignee
2. Edit the trigger
3. Review the conditions and actions of the default trigger, Notify assignee of comment update. Make sure to add this action to your trigger: Other > Notify by > User email | Object > Ticket > (assignee), to send the assignee a notification
4. Click Save