emerge -a dkim-milter
emerge --config mail-filter/dkim-milter
/etc/mail/dkim-filter/dkim-filter.conf: Domain domain.tld
KeyFile /etc/mail/dkim-filter/mydkim.private
Selector mydkim
UMask 000
/var/bind/domain.tld.hosts:mydkim._domainkey.domain.tld. IN TXT "v=DKIM1; g=*; k=rsa; p=yourkeyhere;"
/etc/postfix/main.cf:smtpd_milters = unix:/var/run/dkim-filter/dkim-filter.sock
non_smtpd_milters = unix:/var/run/dkim-filter/dkim-filter.sock
rndc reload
postfix reload
/etc/init.d/dkim-filter start
Test by sending email to autorespond+dkim@dk.elandsys.com.