ATTENTION: if you are using any version of KloxoMR with 2014 in the revision date, DKIM is available and this does not need to be done.
DKIM signing is not available in KloxoMR. It is not KloxoMR problem, it is a qmail-toaster problem. This solution has been around for a while, however I perfected it to work with KloxoMR with minimal changes needed.
First login to ssh on your server.
cd /tmp
yum install perl-Mail-DKIM
wget http://cc-server1.us/dkimsign.pl
wget http://cc-server1.us/qmail-remote.new
cp dkimsign.pl /usr/bin/
chmod 755 /usr/bin/dkimsign.pl
qmailctl stop
mv /var/qmail/bin/qmail-remote /var/qmail/bin/qmail-remote.orig
cp qmail-remote.new /var/qmail/bin/qmail-remote
chown root:qmail /var/qmail/bin/qmail-remote
chmod 755 /var/qmail/bin/qmail-remote
rm /var/qmail/bin/qmail-queue
mv /var/qmail/bin/qmail-queue.orig /var/qmail/bin/qmail-queue
qmailctl start
That will enable DKIM signature of mail sent using qmail-toaster remote. I have found that if you use standard php sendmail function it will not get signed, I suggest piping your php applications through smtp.
You can see that DKIM is working by clicking the "view original" link in Gmail. It will say DKIM: passed.
This will help a lot of your problems. <!-- s:) -->
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