Date: 2012jun27 Keywords: SMTP, Postfix, Sendmail Q. What are some tools for mail server (MTA) administrators? A. These sites can check if you are on a blacklist, have an open relay, etc. http://www.mxtoolbox.com http://www.spamhaus.org/lookup http://www.mydnstools.info/smtprelay https://www.mail-tester.com