Thank you!
This way I know.Request -> History tab
The problem is the following:
1. If the request has been assigned to Technician "User 1" and the request was closed Technician "User 1", notification is sent to email.
2. If the request has been assigned to Technician "User 1" and the request was closed Technician "User 2", Not a notification is sent to email.
There is a variable "the author closed the request" to specify notification rules.
Such As:
Technician: $Technician