amavisd-new genrsa /var/lib/dkim/domain.pem 1024
 
chown amavis:amavis /var/lib/dkim/domain.pem
 
chmod 0400 /var/lib/dkim/domain.pem
 
nano /etc/amavis/conf.d/50-user
 
dkim_key("domain", "dkim", "/var/lib/dkim/domain.pem");
 
"domain"  => { d => "domain", a => 'rsa-sha256', ttl => 10*24*3600 },
 
systemctl restart amavis
 
amavisd-new showkeys
 
amavisd-new testkeys