Setting up DKIM for Postfix doesn't work, what's wrong?

Question

postfix

Hello everyone,
I'm setting up mail for the yaidu.ru server. I followed the Habra article https://habrahabr.ru/post/151904/. But apparently something went wrong, because. DKIM headers did not appear in emails. What could it be?
File /etc/opendkim/keytable:

mail.yaidu.ru:mail:/etc/postfix/dkim/yaidu.ru.private

File /etc/opendkim/signingtable:
yaidu.ru mail.yaidu.ru
Added to postfix config:

milter_default_action = accept
milter_protocol = 2
smtpd_milters = unix:/var/run/opendkim/opendkim.sock
non_smtpd_milters = unix:/var/run/opendkim/opendkim.sock

The socket has been created, you can see it. But signing doesn't work :(

Answer 1

If you send letters without authorization, then you need to register the IP addresses of the clients for which the letters are signed, in
/etc/opendkim/TrustedHosts
check the permissions for all files used.
If that doesn't help, look at what's in the mail.log when sending the email.

Answer 2

For version ≥ 2.6 specify milter_protocol = 6, anything youngermilter_protocol = 2