How do I allow exim to send mail ONLY to certain domains?

Question

linux

Good afternoon.
There is a server with Linux and Exim.
It is necessary to allow exim to send emails only to certain domains.
Now the letters go without restrictions:

fr_router:
  driver = queryprogram
  command = /var/www/exim/exim_filter.py $message_id $sender_address
  command_user = exim
  domains = ! +local_domains
  transport = remote_smtp

I tried experimenting with the domains directive by
creating a list:

domainlist allowed_domains = ukr.net : mail.ru

And replacing the directive with this:

domains = +allowed_domains

But the experiment was not successful - the letters go wherever they want.

Thank you.