Outgoing emails have higher percentage to be delivered at yahoo, google, and hotmail inboxes if they are signed, so can I suggest please to the community to suggest a HowTo on doing this in debian environment. I found a how to by the way about this at http://www.howtoforge.com/postfix-dkim-with-dkim-milter-centos5.1 but the packages and steps are for .rpm environment, if there's a way we can convert this and its step to suite debian environment then I think that would be very helpful.
i think there is a debian package already for that so it should be easy to use the centos instructions for debian
There are instructions here: http://anothersysadmin.wordpress.com/2008/01/16/domainkeysdkim-with-postfix/