Why do users receive two email notifications?

Question

Each time I sent a reply to an email I get a duplicated email in my sent inbox. Why is this?

Answer 

In Zendesk Support, triggers are the mechanism that sends email notifications to users. If any of your agents received a duplicated notification, then your account contains conflicting triggers. 

To fix this issue, open the ticket that sent the duplicated emails and view the events of the ticket. After viewing the events of the ticket, you can modify one of the triggers to not fire in certain circumstances.

For more detailed instructions, see How can I troubleshoot my triggers?