How to Setup DKIM with Qmail Toaster
From Qmailtoaster
1) wget http://qmailtoaster.com/dkim.tgz
2) tar –zxf dkim.tgz
3) cd dkim
4) yum install perl-XML-Simple perl-Mail-DKIM perl-XML-Parser
5) mkdir /var/qmail/control/dkim
6) cp signconf.xml /var/qmail/control/dkim/
7) chown -R qmailr:qmail /var/qmail/control/dkim/
8) dknewkey /var/qmail/control/dkim/global.key > /var/qmail/control/dkim/public.txt
9) perl -pi -e 's/global.key._domainkey/dkim1/' /var/qmail/control/dkim/public.txt
10) qmailctl stop
11) mv /var/qmail/bin/qmail-remote /var/qmail/bin/qmail-remote.orig
12) mv qmail-remote /var/qmail/bin
13) chmod 777 /var/qmail/bin/qmail-remote
14) chown root:qmail /var/qmail/bin/qmail-remote
15) qmailctl start
16) cat /var/qmail/control/dkim/public.txt
17) Create a TXT record on DNS server for the domain you want to set DKIM as shown in the output of step 16.
18) Your DKIM setup is done.
19) Just send test mail on any yahoo email id and check headers. If show error in headers then just wait to reflect DNS.
In order to test your settings, simply send an email to: check-auth@verifier.port25.com and/or check-auth2@verifier.port25.com with the suject of "test" (without the quotes) and "Just testing" in the body (also without quotes). It is best but not required to have a subject and body because this service will also show you how spamassassin rated your email.
You can also use http://www.sendmail.org/dkim/tools to check and confirm you DKIM configuration