email debugging tools
http://feedbackloop.yahoo.net/manage.php
http://www.mailradar.com/domainkeys/
http://www.sendmail.org/dkim/testChecker?domain=oceantara.com&selector=mail&commit=Start+Test
http://domainkeys.sourceforge.net/policycheck.html
http://www.mydigitallife.info/tools/spf-validation-sender-profile-framework-testing-and-checking-tool/
https://www.dnsstuff.com
http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test
http://www.port25.com/domainkeys/
Helpful Websites
https://help.ubuntu.com/community/Postfix/DKIM
https://help.ubuntu.com/community/Postfix/DomainKeys
http://tech.libersoft.it/2009/domainkeys-dkim-with-postfix-quick-way/
http://www.elandsys.com/resources/sendmail/dkim.html
http://www.mail-archive.com/dkim-milter-discuss@lists.sourceforge.net/msg00335.html
http://www.ijs.si/software/amavisd/amavisd-new-docs.html#dkim