Try to setup DKIM on Ubuntu 18.04...
With https://www.linuxbabe.com/mail-server/setting-up-dkim-and-spf i had a "postfix/smtpd[3801]: warning: connect to Milter service local:/opendkim/opendkim.sock: No such file or directory" and i not find any opendkim.sock
With https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-dkim-with-postfix-on-debian-wheezy i had a "Mar 27 02:28:18 manufacture17 opendkim[5983]: terminated with signal 6, restarting
opendkim[6009]: OpenDKIM Filter v2.11.0 starting (args: -p inet:12301@localhost)
postfix/cleanup[6005]: warning: milter inet:localhost:12301: can't read SMFIC_BODY reply packet header: Success"
Email sending and receiving but without DKIM and this is to sad.
How can i fix one of them?
What information can help you to anderstanding this errors?
How can i receive more informative logs?