DKIM setup with multiple domains

HOW

I'm using gentoo in this setup. DKIM-milter 2.8.x ( I think it should work for any minor version of dkim-milter )

 mail-filter/dkim-milter-2.8.3-r1 USE="-diffheaders -ipv6"

Create the private/public keys for each domain

cd /etc/mail/dkim-filter
mkdir keys

mkdir keys/d3xt3r01.tk
dkim-genkey -r -s mydkim -d d3xt3r01.tk
mv mydkim.private keys/d3xt3r01.tk/mydkim
mv mydkim.txt mydkim.d3xt3r01.tk.txt
chmod 600 keys/d3xt3r01.tk/mydkim

mkdir keys/eniasan.ro
dkim-genkey -r -s mydkim -d eniasan.ro
mv mydkim.private keys/eniasan.ro/mydkim
mv mydkim.txt mydkim.eniasan.ro.txt
chmod 600 keys/eniasan.ro/mydkim

mkdir keys/velour-services.ro
dkim-genkey -r -s mydkim -d velour-services.ro
mv mydkim.private keys/velour-services.ro/mydkim
mv mydkim.txt mydkim.velour-services.ro.txt
chmod 600 keys/velour-services.ro/mydkim

chown -R milter:milter keys

It's pretty straight forward.