Apr 9 09:40:14 rx200 mail.info opendkim[4396]: C03DE1014429:
foobar.example.com [192.0.2.10] not internal
It seems that the domain you want to sign is not in the KeyTable or
SigningTable! Note that if you put "refile:" before config file path in
/etc/opendkim.conf the syntax changes!
If
SigningTable refile:/etc/opendkim/SigningTable
then
*@mydomain.tld mydomaintld
If
SigningTable /etc/opendkim/SigningTable
then
mydomain.tld mydomaintld
Note that the dot (.) must not be in the second column. For me the
refile works better.