Tim, I went to register for the bugzilla and found that the confirmation request from 188.8.131.52 was rejected by postfix because 184.108.40.206 does not provide a proper reverse lookup causing: smtpd_client_restrictions = reject_rbl_client sbl.spamhaus.org, reject_unknown_client It is 'reject_unknown_client' causing the rejection. From: http://www.postfix.org/postconf.5.html the rejection is caused when: 1) the client IP address->name mapping fails, 2) the name->address mapping fails, or 3) the name->address mapping does not match the client IP address. I'm no postfix expert, but to let the confirmation through, I just removed 'reject_unknown_client'. If there have been people who don't get the confirmation emails, this may one reason why :) The actual postfix rejection was: Feb 28 16:22:21 nirvana postfix/smtpd: warning: 220.127.116.11: address not listed for hostname pearsoncomputing.net Feb 28 16:22:21 nirvana postfix/smtpd: connect from unknown[18.104.22.168] Feb 28 16:22:22 nirvana postfix/smtpd: NOQUEUE: reject: RCPT from unknown[22.214.171.124]: 450 4.7.1 Client host rejected: cannot find your hostname, [126.96.36.199]; from=<bugs@...> to=<snip> proto=ESMTP helo=<vali.starlink.edu> Feb 28 16:22:22 nirvana postfix/smtpd: disconnect from unknown[188.8.131.52] Somebody smart with postfix and bind can probably tell you what the exact issue is. Just looking, I see a helo from vali.starlink.edu and the "warning: 184.108.40.206: address not listed for hostname pearsoncomputing.net" -- David C. Rankin, J.D.,P.E.