In my previous post about DKIM  I forgot to mention one critical item, how to get Postfix to actually talk to the DKIM milter. This wasn’t a bad thing because it turned out that I hadn’t got it right.
I had configured the DKIM milter on the same line as the milters for ClamAV and SpamAssassin – in the smtpd_milters section. This was fine for relaying outbound mail via my server but didn’t work for locally generated mail. For locally generated mail Postfix has a directive named non_smtpd_milters which you need to use. So it seems that a fully functional Postfix DKIM milter configuration requires adding the following two lines to /etc/postfix/main.cf:
smtpd_milters = unix:/var/run/dkim-filter/dkim-filter.sock
non_smtpd_milters = unix:/var/run/dkim-filter/dkim-filter.sock
This also required an update to the SE Linux policy. When I was working on setting up DKIM I also wrote SE Linux policy to allow it and also wrote policy for the ClamAV milter. That policy is now in Debian/Unstable and has been approved for Lenny. So I now need to build a new policy package that allows the non_smtpd_milter access to the DKIM milter and apply for it to be included in Lenny.
SE Linux in Lenny is going to be really good. I think that I’ve already made the SE Linux support in the pre-release (*) of Lenny significantly better than Etch plus all my extra updates is. More testers would be appreciated, and more people joining the coding would be appreciated even more.
(*) I use the term pre-release to refer to the fact that the Lenny repository is available for anyone to download packages.