Iredmail took over the main domain along with the mail. How to fix?

Question

Nginx

Put iredmail on mail.example.ru. After setting up, mail worked on mail.example.ru, but when switching to example.ru, mail also opened. With my extremely modest knowledge of nginx, I changed the server name from _ to mail.example.ru, restarted and did not help. How to remove mail from the main domain? In addition to the server name, I did not change anything, I set it according to this instruction

Answer 1

Create a separate nginx config for the example.ru domain.
Specify a separate directory as Root.