I made a fresh install on a Ubuntu 18.04 server of the latest Virtualmin release. Got everything up and running, except the fact that my DKIM signature is not included in the email header when sending emails.
Initially, my mail.log was showing
Main postfix/cleanup: warning: connect to Milter service inet:localhost:8891: Connection refused, but then I commented out the following two lines:
#smtpd_milters = inet:localhost:8891
#non_smtpd_milters = inet:localhost:8891
/etc/postfix/main.cf, restarted opendkim and postfix and the error was gone - but my problem wasn't solved. The DKIM is still not being included in the email headers. Any ideas?