Hello, Thanks in advance to answer to my problem. I actually follow the howto http://howtoforge.com/quick-and-easy-setup-for-domainkeys-using-ubuntu-postfix-and-dkim-filter I follow all the point and everything seem to work perfectly but when I send an email to my yahoo account, I don't have a domainkey valid. I have a debian lenny postfix works, and dkim-filter too. Unfortunately I can't do the part with bind9 because I use godaddy to manage my domaine name. So I add the public key in godaddy. If you need information or other think to help me I will give you. Thanks again.