Zimbra Collaboration Suite 7.1
Debian 6.0

I have searched and tried to get this working for 2 days now and nothing I have attempted has worked. I have followed countless tutorials online (most written for centos and rpm packages) and tried both dkim-filter and opendkim. I have tried using setting the master.cf (which never saves, even in su - zimbra... Even tried sudo in su - zimbra which ask for a password then tells me its incorrect...), setting the milter setting in zimbra admin with no luck...

Can someone please help me out with this, this simple thing which should have taken 3 minutes has turned into a 3 day project that doesnt seem to have an end.