Sending emails after a issue has been assigned

How do you send a email if a Issue hasn’t been assigned to yet?
I made a custom doctype and need to send a email if a ticket hasnt been assigned to someone in a hour

use the Email Alert option to achieve it.
use filters to set conditions.

ok thank you, ill try that out now

i have fields:
time opened - time we opened the issue and saved the fields

time reported - time we recieved issue

time closed - time we closed and issue

how do i set it so the email sends a hour later?

Also my doctype on desktop doesnt show the red icon with the number of opened custom issues. How do i add that manuallY? i read the post where you code it in the file in the core folder but how do i?