There is an option in the administrative panel in the settings section and within alerts and notices where you should check in the new ticket alert "department members". That should be the one.

I had the same issue this week but the new ticket email was being sent in other machine I installed it. The way I was able to solve it in the new machine was to use the same email settings I had in the old one. Apparently the email used as admin is the one that sends that particular kind of email because when I was using an email that was not from gmail with the admin the new ticket email was not being sent.