1.11 is no longer supported due to security issues. Please upgrade to 1.12.
1.11 also does not support PHP 7.3 so you will likely run into issues running it.
In order to troubleshoot this further we would first need you to upgrade and then we would need to know the address it is being sent to, and your email configuration(s) and and send emails the ticket uses (due to the department it is in)