[PLUG] Resolving a DNS/postfix issue

[Rich Shepard]

   I'm hoping one (or more) of you professional SysAdmins can point me to the
resolution of this problem.

   I'm trying to subscribe to a mail list run my Mailman, but postfix rejects
the confirmation messages because it cannot resolve the host name from the
IP address; e.g,:

Oct 11 06:53:36 salmo postfix/smtpd[27785]: NOQUEUE: reject: RCPT from
unknown[67.23.35.254]: 450 4.7.1 Client host rejected: cannot find your
hostname, [67.23.35.254]; from=<dabo-users-bounces at leafe.com>
to=<rshepard at appl-ecosys.com> proto=ESMTP helo=<marge.leafe.com>

   I added leafe.com to /etc/postfix/rhsbl_sender_exceptions (as OK), rebuilt
the database using /usr/sbin/postmap, reloaded postfix, and still no joy.

   My assumption is the issue is at the other side's DNS server. Am I
incorrect in this assumption? Is there anything I can do to resolve this
issue from my desk?

TIA,

Rich